Glossary of Botanical Terms

Glossary of Botanical Terms Cover

This Glossary of Botanical Terms currently contains over 4000 terms relating to botany, gardening, horticulture and landscape architecture. 

Feel free to just browse the page or use the real time search box for keywords. To revert the search, just click the "Clear" button, should it be necessary. 

The Glossary of Botanical Terms has been restored from The Wayback Machine due to the fact that it had been archived some time ago and therefore disappeared from the Internet. We have lovingly restored the content and made the search more efficient. Please enjoy and in case you have questions or additions to this list, then please do not hesitate to contact us.

Clear
-merous

A suffix preceded by an Arabic number or numeric prefix such as tri-, indicating how many of each part a flower possesses; 5-merous would be a flower with 5 sepals, 5 petals, etc., while trimerous would have three of each part.

A horizon

The uppermost layers of soils consisting of partly decomposed plant remains and relatively fresh leaves and other plant debris; the surface mineral layer, high in organic matter and dark in color; and the lighter colored layer where leaching of solutes and suspended materials occurs.

AARS

An acronym representing the name All-America Rose selections, Inc., an association of commercial rose growers that tests and approves new rose varieties for commercial use.

abaxial

Facing away from the axis.

abbreviated (syn. abridged)

Shortened, as when one part is shorter than another.

aberrant

Atypical or unusual; not normally occurring.

abiogenesis

Spontaneous generation of life from nonliving material.

abiotic

Nonliving, as opposed to biological.

abiotic stress

Nonliving environmental factors such as frost, drought, excessive heat, high winds, etc., that can have harmful effects on plants.

abiotic transformation

Any process in which a chemical in the environment is altered by nonbiological mechanisms, e.g., by exposure to sunlight.

abortion

Imperfect development or nondevelopment of an organ.

abortive

Defective or barren. Describes especially but not exclusively reproductive structures.

above

1. Refers to the adaxial (upper/outer) surface of a leaf, petal, sepal or scale. 2. Refers to the part of a stem, bulb, tuber, branch, or inflorescence that is the greatest distance from the attachment, following the stem/branch; if a branch arches with a flower at the tip drooping nearly to the ground, the flower is said to be above the highest point of the branch.

abrade

To scrape off.

abrupt

Suddenly narrowed or cut off.

abscisic acid (abr. ABA, syn. abscisin)

A plant hormone that promotes leaf.

absciss-layer

A belt of tissue preparing for separation, especially at the connection of a leaf to the stem.abscission, fruit drop, and seed dormancy, and has an inhibitory effect on cell elongation.

abscission (adj. abscissile)

The normal shedding of leaves, flowers or fruit from a plant at a special separation layer, or abscission zone.

abscission zone

The area of separation when a plant sheds a leaf, flower or fruit.

absent petiole

A leaf without a petiole; sessile.

absorb (n. absorption)

To suck up or take up, e.g., plant roots absorb water.

absorbents

Antacid herb.

absorption spectrum

A graph of the amount of light a substance absorbs, plotted as a function of energy, frequency, or wavelength.

acariasis

An infestation with or a disease caused by mites.

acarodomatia

Domatia which have adapted to provide shelter to beneficial mites.

acaulescent

A plant that is stemless or apparently so, or with the stem subterranean.

accelerators

Admixtures that decrease the setting time of concrete by increasing the rate of hydration.

accessory

Auxiliary, subsidiary; as the parts of a flower beyond the necessary male and female organs, such as petals and sepals.

accessory bud

Buds which are at or near the nodes but not in the axils of the leaves.

accessory fruit

A fruit, or group of fruits derived from a singleflower, in which the conspicuous, fleshy portion develops from the receptacle and is shed with the true fruit(s) attached.

accessory organs

Parts of a flower that are not directly connected with male and female organs, e.g., petals and sepals, etc.

acclimate (n. acclimation)

To adapt to a new environment, or a change in the environment.

acclimatization (syn. adaptation)

The physiological process by which an organism adapts to a new environment.

accrescent

Gaining in girth or length with age or following fertilization, or growing together, as the calyx of some plants after flowering, such as the ground cherry.

accumbent

A cotyledon having the edges lying against the radicle.

aceriform

Shaped like a maple leaf; deeply lobed.

acerose

Sharp, solid, needle-like.

achene

A small dry and hard 1-celled, 1-seeded indehiscent fruit.

achenecetum

A cluster of small seeds (achenes), as in buttercups, Ranunculus.

achenocarp

Any dry fruit that does not open by itself.

achlamydeous

Without a perianth, e.g., the flowers of a willow.

achlorophyllous

Lacking chlorophyll; appearing without green color.

acicular

Needle-shaped. If solid, may be either round or grooved in cross section.

aciculate

1. Describes a surface that is etched with fine lines, as if scratched by a needle. 2. Marked with what appears to be pin pricks, usually arranged at random.

acid rain

Rain which has turned acidic due to the presence of sulfur or nitrogen oxides in the atmosphere. Acid rain can harm and even kill plants and aquatic life.

acid soil (adj. acidic)

Soil with a pH level below 7 is considered acidic; also called sour.

acidifier

An additive that decreases the pH (and increases the acidity) of soil.

acidophile (adj. acidophilic)

A microorganism that can, or must, live in an acidic environment. See also: alkaliphile.

acidulous

Slightly acidic.

acinaceous

Covered or filled with kernels.

acinaciform

Shaped like a half moon.

acinose

Resembling a bunch of grapes.

acondylose

Stems which lack joints or nodes.

acorn

The hard-shelled, one-seeded fruit of the oaks (Quercus) which consists of a nut which is partly enclosed by the cupule, or cap.

acotyledonous

Having no seed leaves, or cotyledons.

acre

Land measurement of 43,560 square feet, roughly the size of a football field.

acrid

Harsh and bitter in taste.

acrocarpous

In mosses, having the sporophyte terminal on a stem or ordinary branch.

acrocidal capsule

A dry fruit which dehisces by slits at the terminal.

acrodome

With the main veins ending at the leaf tip.

acrodromous

Describes leaves with two or more primary or strongly developed secondary veins running in convergent arches towards the apex. Arches not recurved at base. See also: brochidodromous, eucamptodromous, semicraspedodromous.

acropetal

Developing in a succession from the base and towards the apex. See also: basipetal.

acroscopic

Facing upwards, towards the apex of the axis on which it is borne. See also: basocopic.

acrostichoid

Having sporangia apparently scattered on the surface of the fertile lamina.

acrotonic

Describes flowering seasonal shoots which produce leaves below the inflorescence. See also: basitonic.

actinomorphic

Refers to flowers that can be divided into symmetrical halves along any diameter. See also: zygomorphic.

actinostelic

Refers to a vascular strand where ribs radiate outward.

active transport

The movement of a chemical substance by the expenditure of energy through a gradient (as across a cell membrane) in concentration or electrical potential and opposite to the direction of normal diffusion.

actual

As in actual nitrogen; calculating the amount of the mineral present, e.g., calculating a 25-pound bag of fertilizer containing 22 percent of nitrogen as the equation 25 pounds X .22 = 5.5 pounds of actual nitrogen.

aculeate

Prickly; beset with prickles.

aculeiform

Shaped like a prickle.

aculeolate

Beset with diminutive prickles.

acumen

The gradually tapering narrow point of an acuminate leaf.

acuminate (n. acumination)

The shape of a tip or base of a leaf or perianth segment where the part tapers gradually and often in a concave manner.

acutangular

Refers to a stem that is sharply angled.

acute

Terminating with a sharp or well defined angle.

acyclic

Arranged in spirals as opposed to whorls.

adaptability

Proficiency of an organism to make changes improving survivability and reproduction in its habitat.

adaptation (alt. adaption)

1. The ways an organism becomes better fitted to survive and reproduce in a particular environment. 2. A genetically changing characteristic that raises an organism's ability to survive.

adaptedness

The genetic characteristics by which an organism is suited to its environment.

adaptive capacity

The genetically set range or flexibility of reactions of an organism enabling it to respond in different ways to differing conditions.

adaptive radiation

The evolution of new species or subspecies to fill unoccupied ecological niches.

adaptive selection

The evolution of comparable forms in separate but ecologically similar areas.

adaxial

Facing toward the axis, as the upper surface of a leaf.

additive

Material added to a substance, such as fertilizer, to better enable it to perform the desired function.

adenosine diphosphate (abr. ADP)

An ester of adenosine that is reversibly converted to ATP for the storing of energy by the addition of a high-energy phosphate group.

adenosine triphosphate (abr. ATP)

A phosphorylated nucleoside that supplies energy for many biochemical cellular processes by undergoing enzymatic hydrolysis especially to ADP. An energy-rich phosphorous compound that is important in the transfer of energy in organisms.

adherent

Joined, but not united.

adiabatic

Refers to an event in which heat is neither gained nor lost.

adjacent

Next to each other, but without touching or overlapping.

adjustment

Functional, never structural, changes by which an organism becomes better suited to its environment. See also: adaptation.

admixture

A material other than water, aggregates, or cement that is used as an ingredient of concrete or mortar to control setting and early hardening, workability, or to provide additional cementing properties.

adnate

United; fused, as the inferior ovary with the calyx-tube. Adnate anther: one attached for its whole length to the inner or outer face of the filament.

adobe

A fine calcareous clay or silt, often used for construction purposes.

adpressed

Pressed flat against another organ.

adsorption

The attachment of molecules or ions to outer surfaces or interfaces.

advance growth (syn. young growth)

Seedlings and saplings appearing under the canopy ready to fill in forest openings made available by the death of a mature tree from logging, lightning kills, etc.

adventitious

Describes an organ growing where it is not normally expected, e.g., roots growing from a stem.

adventitious root (syn. stem root)

A root that arises from a stem, rather than from the primary root.

adventitious species

An alien or exotic species; an invasive species.

adventive

Describes an exotic species recently introduced to an area or imperfectly naturalized.

adventive taxa

Organisms that were not native to an area, and have now naturalized.

adze (alt. adz)

A tool for shaping wood having a curved blade arched downwards and at a right angle to the handle.

aelophilous

Refers to plants which spread seeds or pollen by wind.

aeolian (alt. eolian)

Refers to the wind, or to soil which has been moved by wind.

aerate

To supply or impregnate with air.

aerating root

A root structure that rises above ground, usually above water, to allow the plant to absorb air.

aeration

The processes by which air and other gases in a medium are exchanged or refreshed.

aerenchyma

Tissue with thin walled cells separated by large, gas-filled spaces that facilitates gaseous exchange and maintains buoyancy; typical of aquatic plants.

aerial

Refers to any plant part that is above water in aquatic plants; less often used with terrestrial plant parts found above ground.

aerial photograph

A map-like picture taken of the ground from high in the air, showing roads, fields, and other man-made objects as well as natural features such as rivers.

aerial roots

1. Roots borne wholly above ground, as the attachments of vine forms of Toxicodendron radicans which penetrate tree bark. 2. Rooting shoots of epiphytes.

aerobic (n. aerobe)

Living, active, or occurring only in the presence of oxygen.

aerobiosis

All life that grows in the presence of free oxygen.

aeroplankton

Microorganisms which float in the air, as plankton floats in water.

aerotaxis

An involuntary response of a living thing to a gas, such as a plant curving toward a more concentrated source of carbon dioxide.

aerotropism

An organism's growth determined by the presence of oxygen.

aestidurilignosa

Woodland with mixed evergreen and deciduous hardwoods.

aestival (alt. estival)

Appearing during the summer season. See also: aspection.

aestivation

1. Estivation. 2. The arrangement of the perianth or their lobes in an unexpanded flower bud. See also: vernation.

affinity

That relationship between organisms which shows they share a common origin; used occasionally to show the similarity among communities.

affixed

Fastened upon.

afforestation

The process of starting a new forest in an area where none existed; to do the same to replace a previous growth is reforestation.

afoliate

Without leaves.

after-ripening

1. Metabolic changes that must take place in a seed to overcome dormancy. 2. The dormancy period following seed formation, necessary for embryo changes that insure germination.

aftermath

1. A second growth crop, also called a rowen. 2. The outcome, especially of a disaster, as in the aftermath of a forest fire.

agamic

Asexual.

agamogenesis

Asexual reproduction, as by budding, cell division, or parthenogenesis.

agamospecies (alt. agameon, syn. binom)

A group of individuals in which reproduction is almost exclusively by asexual means.

agamospermy

Apogamy where sexual union is not completed, yet the embryo is produced from the inside layer of the female gametophyte.

agamosporous

Having a life cycle in which chromosome segregation and recombination does not take place.

agamous

Without stamens or pistils; neuter, sterile.

agar

A gelatinous substance produced by red algae, often used as a culture medium.

agaric

1. The dried fruiting body of a fungus formerly used in medicine. 2. Any of a family (Agaricaceae) of fungi with the sporophore usually resembling an umbrella and with numerous gills on the underside of the cap.

age and area

The hypothesis that the larger the area covered by a species, the older that species is.

age class (syn. even aged)

Refers to a stand in which all the trees or other perennials started growth in the same regeneration period. See also: monoculture.

age distribution

The classification of groups within a community according to age or certain periods such as prereproductive, reproductive, postreproductive.

ageotropic (alt. apogeotropic)

Said of parts that would be expected to grow as gravity pulls, but instead grow upward, such as the knee roots of cypress, Taxodium spp./I>.

agglomerate

Together in a head, as the florets of red clover, Trifolium pratense; clustered.

agglutinate

Stuck together, as in pollen masses of orchids.

aggradation

The gradual filling of depressions in the earth's surface by soil deposition, such as the deposition at a lake's bottom; or the opposite, the wearing away of mountain tops, reaching toward a level surface.

aggregate

1. Clustered. In mosses, applied to two or more sporophytes from one perichaetium. 2. Composed of mineral crystals of one or more kinds or of rock fragments. 3. A material such as sand or gravel mixed with a binder, such as cement, to produce mortars and concrete. 4. A group of closely-related species.

aggregate flowers

Crowded into dense clusters or tufts, as in Scabiosa atropurpurea.

aggregate fruit

Describes a fruit, such as a raspberry, which consists of a fused cluster of several fruits, each one formed from an individual ovary. See also: syncarp.

aggregate species

A group of species that are so closely related that they are regarded as a single species.

aggregation

The coming together of organisms into a group, such as seedlings growing near the base of a parent tree. See also: community.

aging

When said of a lake, refers to the enrichment of waters, rapid growth of aquatic plants, and sedimentation which accelerate the death of a lake.

agonistic behavior (alt. agonistic behaviour)

Aggressive or defensive actions, such as fleeing or fighting, brought on by the interaction between individuals usually of the same species.

agrarian zone

That portion of a jurisdiction that can be or is farmed.

agrestal

Growing wild; especially weed plants growing on farms.

agrestic

Rural; rustic.

agrobiology

The study of plant nutrition and crop production in relation to soil control.

agroforestry

Land management for the simultaneous production of crops and trees.

agrology (syn. edaphology)

The study of soils.

agronomy (adj. agronomic)

The theory and practice of soil management and field crop production.

agrophilous

Refers to organisms which grow best in cultivated fields or other manmade areas.

agrostology

The branch of systematic botany which encompasses grasses; graminae.

aianthous

Flowers all year; semperflorus.

aiphyllus

Evergreen.

air layering (alt. air-layering, syn. Chinese layering, syn. gootee, syn. marcotting)

A method of propagation where a cut is made in a woody stem and surrounded by damp peat moss held in place by a wrap. When roots form, the stem can be removed and planted.

air mining

Processing air to recover minerals in suspension or solution.

akene

A dry, one-seeded indehiscent fruit, with the pericarp fitting closely around the seed.

ala (pl. alae)

Wing; in ferns, the narrow membrane laterally bordering a stipe, rachis, or costa.

alar

Describes the cells at the basal angles of the leaf, commonly different from the cells of the main part of the leaf, being shorter and often nearly square, or inflated and hyaline, and often highly colored.

alate (syn. aliferous)

Winged.

albedo

The proportion of incident radiation, usually light, that is reflected by a body such as a cloud.

albescense (adj. albescent)

The act of turning white; whitish.

albidus

Whitish.

albino

A flower that lacks normal color; white.

albumen

Starchy and other nutritive material in a seed, stored as endosperm inside the embryo sac, or as perisperm in the surrounding nucellar cells; any deposit of nutritive material accompanying the embryo.

albuminous

Having albumen.

albuminous cell

A gymnosperm phloem parenchyma cell closely associated with an adjacent sieve cell.

aletophyte

A plant growing in a mesic habitat.

alga (pl. algae)

A general name for the single-celled plant plankton, seaweeds, and their freshwater allies.

algae bloom

Rapid growth and death of aquatic plants, especially during hot weather in highly nutritious water.

algal layer

A thin layer of green or blue-green algae lying just beneath the cortex of a lichen.

algin

A gelatinous substance produced by brown algae, used in food and pharmaceutical preparations.

algoid

Resembling algae.

algology

The study of algae.

alien

An exotic; an introduced plant which has naturalized.

aliferous

Winged.

aliquote

The constant of temperature required for the development of a certain stage in the life cycle of an organism. See also: temperature summation.

alkali

A soluble salt obtained from the ashes of plants and consisting largely of potassium or sodium carbonate, e.g., a hydroxide or carbonate of an alkali metal, having marked basic properties. 2. Alkali metal. 3. A soluble salt or a mixture of soluble salts present in some soils of arid regions in a quantity that is detrimental to agriculture.

alkali reserve

The total amount of dissolved substances predisposed to maintain the normal alkalinity of a body of water or an organism's internal body fluids.

alkali sink

A land basin in which water evaporation produces high salt concentrations that may, or may not, support salt marsh vegetation.

alkaline (adj. alkalinity)

1. Of, relating to, containing, or having the properties of an alkali or alkali metal. 2 A base; having a pH of more than 7.

alkaline soil (alt. alkali soil, syn. basic soil)

Soil with a pH level above 7; also called sweet.

alkaliphile (alt. alkalophile, syn. basophile, adj. alkaliphilic)

An organism that prefers, or can tolerate, alkaline conditions, typically in the range of pH 8-11. See also: acidophile.

allagostemonous

A flower having stamens attached to both the petal and receptacle.

allantoid

Sausage-shaped.

allee

A walkway lined with trees or tall shrubs.

allele (alt. allelomorph, syn. dominant character)

Any of the alternative forms of a gene that may occur at a given locus, one provided by each parent and determining charateristics such as eye color.

allelopathy (adj. allelopathic)

The inhibition of growth of one plant species by another due to the release of chemical substances.

allergen (adj. allergenic)

A substance which induces allergic symptoms like rash, inflammation, etc.

allergy

Sensitivity resulting in reactions such as rash, inflammation, etc., when exposed to an allergen, e.g., pollen, strawberries, etc.

alley

A garden or park walk bordered by trees, shrubs, or flower beds.

alliaceous

Having the smell or taste of garlic.

alliance

A group of plant associations classed together on the basis of similarities in floristic and sociological characters.

allochoric

Refers to a species occurring in two or more similar communities in the same region.

allochthonous

Originating from outside a system, such as the leaves of terrestrial plants that fall into a stream. See also: autochthonous.

allogamy

Reproducing by cross-fertilization.

allogenic succession

The replacement of one kind of community with another because of a change in the environment which was not produced by the plants themselves, e.g., a decrease in soil moisture.

allohexaploid

Having sex genomes with one or more sets derived from a species different from the other sets.

allopatric

Refers to two or more species having nonoverlapping ranges of distribution. See also: sympatric.

allopelagic

Refers to any organism occurring at any depth of the ocean.

allopolyploid

A polyploid individual or strain having a chromosome set composed of two or more chromosome sets derived more or less complete from different species.

allotetraploid

Having four genomes with two sets (rarely one) coming from a different species than the others.

allotrophic

Refers to lakes or ponds which receive organic materials from the surrounding land by washing.

alluvial

Describes something related to, or caused by, a river or stream, such as alluvial deposits.

alluvial fan

A delta at the mouth of a stream or river formed by the depositing of transported materials when the flow lessens.

alluvial soil

Soil deposits at the mouth of a stream or river, characterized by little or no modification of the original transported material by soil-forming processes.

alluvion

Detritus and sediments deposited by streams or the action of waves and currents in larger bodies of water; this contributes to the gradual addition of land and loss of lake or wetland.

alluvium

Sediments which were transported by a stream or river, then deposited when the stream flow lessened. See also: alluvion.

alm

A high mountain meadow, either alpine or subalpine.

almanac

Calendar to which astronomical data and various statistics are added.

alpage

An upland pasture consisting of natural plants which are used for grazing animals at the height of summer.

alpine

1. A plant native to a mountainous region. 2. Refers to the area of a mountain above the tree line, or to organisms which grow there.

alteratives

Herbal medicines which can work a gradual change in the system.

alternate

Describes leaves that are not opposite to each other on the axis, but arranged singly at different heights.

alternation of generations

The complete life cycle of plants with very different sexual and asexual phases, such as the succession of haploid gametophytes and diploid sporophytes found in ferns, Pteridophyta.

alternes

Two or more types of communities alternating with each other in a more or less restricted area.

alternitepalous

Describes floral parts, inserted alternately with the tepals.

altherbosa

Communities with tall herbaceous plants, especially in denuded forest areas.

altimeter

An instrument for determining altitude.

alulate

Having a very narrow wing.

alvar

A Swedish term for a habitat type consisting of dwarf shrubs.

alveolate

Honeycombed; having angular depressions separated by thin partitions.

alveolation

A honeycombed condition.

amanthophilous (syn. ammocolous, alt. ammophilous)

Refers to organisms which live in sand.

amendment

Alteration or change, especially for the better, as when adding a soil amendment.

amensalism

The state or interaction in which one organism is reduced while another is not influenced. See also: commensalism.

ament

A catkin, or scaly spike.

amentaceous

Refers to plants which produce catkins.

amentula

Applied to the special antheridia-bearing branches of Sphagnum.

American Rose Society (abr. ARS)

An educational, nonprofit organization dedicated exclusively to the cultivation and enjoyment of roses.

amethystine

Violet-colored.

ametoecious

Refers to a parasite which is restricted to a single host, i.e., species specific.

amino acid

One of the organic, nitrogen-containing units of which proteins are composed.

amitosis

Direct division of the nucleus of a cell without mitosis.

ammate

A compound of ammonium sulfate, often used as an herbicide.

ammonification

The formation of ammonia compounds from organic materials containing nitrogen.

amnion (alt. amniotic fluid, alt. amniotic waters)

The liquid surrounding an embryo while in uterus or in an egg.

amniote

Animals whose embryos develop within a fluid-filled sac, e.g., some reptiles, birds and mammals.

amorphous

Shapeless, a form not regular or predictable.

amphibious

Capable of living on land or in the water.

amphicarpic

Producing two different types of fruits; sometimes said of plants which bear more than one crop each year.

amphicarpogenous

Producing fruit above ground which then becomes buried, e.g., peanuts, Arachis hypogaea.

amphichromatism

Having flowers of different colors appearing in different seasons.

amphicryptophyte

A marsh plant with some underwater vegetative parts.

amphidiploid (alt. amphiploid)

A tetraploid having two sets of genomes coming from different parent stock.

amphigeal

Producing two types of flowers, one coming up directly from the root, the other on upper stems.

amphigean

Native of both Old and New Worlds.

amphigenesis

The joining of gametes to form a zygote.

amphigenetic

Refers to an organism or a part of the growth cycle that produces zygotes.

amphimixis

Sexual reproduction; the joining of parental characters.

amphiphyte

A plant growing in the edge of wetland and water showing amphibious characteristics.

amphiploid (alt. amphidiploid)

A variation on polyploid in which there are two sets of chromosomes, each set coming from a different species.

amphirhinal

Refers to an organism with two noses.

amphitheater (alt. theatre, syn. theater)

A hillside or depression with tiers or terraces cut into it, resembling a classical outdoor theater and usually used for that purpose.

amphithecium

The outer layers of cells of the sporangium.

amphitropous

Half inverted and straight, with the hilum lateral; an ovule that is curved back along its funiculus so that the base and micropyle are close together. Describes an ovule or a seed.

amphoteric

Refers to the ability of a substance to react either as an acid or a base.

amplectant

An organism or organ with the ability to clasp or twine, like a tendril.

amplexicaul

Clasping the stem.

ampliation

The process of enlarging or amplifying.

ampule (alt. ampulla, adj. ampulliform, adj. ampullaceous)

A hollow flasklike organ shaped like a bladder or squat round bottle; e.g., the traps and floats such as those found on the leaves of Nepenthaceae or Utricularia.

anabiont

A plant that produces flowers and fruits many times; a perennial.

anabiosis

Revival of an organism after apparent death, like the resurrection plant, Anastatica.

anabolism

The process of building up protoplasm from simple substances.

anadromous

Having the first lobe or segment of a pinna or frond arising toward the apex/tip.

anaerobe

An organism which can survive in the absence of oxygen.

anaerobic

Describes a process that occurs with little or no oxygen present.

anaerobic respiration

Gaseous exchange in which the hydrogen removed from the glucose during glycolysis is combined with an organic ion instead of oxygen.

anaerobiosis

The existence of life without oxygen.

anaerophytobionts

Soil flora which exist without oxygen.

analgesic

An herbal medicine which can relieve pain.

analogous

Of similar function, but of different evolutionary descent. See also: homologous.

anamniote

An animal lacking embryonic membranes or amnion.

anandrous

Refers to flowers that have no stamens.

anastomose (v. anastomosing, adj. anastomosed)

Netted, as are veins in a leaf.

anastomosing

Connecting by cross-veins and forming a network.

anastomosis

The connection of various parts to form a network, as in leaf veins.

anatomy

The study of the structure of an organism and the relationship between its parts.

anatropous

An ovule that is inverted and straight, with the micropyle next to the hilum and the radicle consequently inferior.

anauxotelic

Describes inflorescences, parts of inflorescences or axes that do not end in a flower, and in which growth does not continue beyond the flowering region. See also: auxotelic.

anchor root

A large root serving mainly to hold a plant in place in the soil.

anchor-ice

Frozen water that forms at the bottom of a stream.

ancipital (adj. ancipitous)

With both edges sharp, as some flattened stems.

androconia

Modified scales on the wings of butterflies, e.g., Lepidoptera, that produce a sexually attractive odor. See also: pheromones.

androdioecious

A plant breeding type in which a species, to produce seeds, must have a male plant with flowers having only stamens and a bisexual plant with flowers having both stamens and pistils. See also: dioecious.

androecium

Refers collectively to the stamens of one particular flower.

androgynophore

A stalk bearing both the androecium and gynoecium of a flower above the perianth.

androgynous

1. Of an inflorescence composed of both staminate and pistillate flowers. 2. With antheridia and archegonia in the same cluster of leaves, i.e., either synoicous or paroicous.

andromonoecious

Refers to species that have bisexual and male flowers on the same plant.

androphile

A plant that grows most successfully around humankind.

androphore

A stalk bearing the androecium.

androsporangium

The receptacle in which androspores are formed.

androspore

The minute reproductive body, which gives rise to the (often exceedingly obscure) male plantlet in the sexual generation.

anemochore (alt. anemochory)

Dispersal of organisms, such as seeds, by wind. See also: diaspore, disseminule.

anemogram

The graphic record of wind velocity made by an anemograph.

anemograph

An automatic instrument for graphic recording of wind sp.ed.

anemometer

An instrument that measures wind sp.ed, but does not necessarily record it. See also: anemograph.

anemophious (alt. anemophilous)

Refers to plants which are pollinated almost exclusively by wind. See also: anemochory, entomophilous.

anemoplankton

Microorganisms transported by wind.

anemotaxis

The reaction to wind experienced by a free-moving organism.

anemotropism

Movement or growth of cells or organisms in response to wind.

aneroid barometer

An instrument that precisely measures atmospheric pressure to allow calculation of altitude.

aneuploid

Refers to the presence of an irregular number of chromosomes, higher or lower than multiples of the haploid number. See also: euploid.

anfractuose (alt. anfractuous)

1. Tightly twisted together. 2. Closely sinuous.

angiosperm

A flowering plant with ovules contained inside the ovary.

angiospermous

Having the seeds borne within a pericarp.

angle of repose (syn. critical slope)

The maximum degree of gradient on which soil or loose rock remain stable.

angled

Having evident ridges.

angular (alt. angulate)

Angled. Refers to an organ that shows a specific number of angles, e.g., mints, Labiatae, which have stems that are 4-angled, and are square in the cross section.

angular cells

See also: alar.

angustifolia

Narrow leaves.

angustiseptal

Having a fruit with narrow partitions, as the silicle of Cruciferae.

angustiseptate

Having narrow partitions. See also: latiseptate.

anhydrous

Refers to a substance which contains no water, like anhydrous ammonia.

animal unit

A standardized measure to understand the needs of different kinds of livestock in relation to forage resources. A mature cow of about 1000 pounds (455 kg.) is the standard unit, and the feed needed is equal to one horse, one mule, five sheep, five swine, five goats, or eight geese.

animal unit month

A measure of forage needed to maintain one animal unit for 30 days.

anion

A negatively-charged ion, such as chlorine. See also: cation.

aniso-

A prefix meaning unequal or dissimilar.

anisophyllous

Refers to paired leaves which are different in size or shape, common in trailing stemmed gesneriads.

anisophylly

The presence of two kinds of leaves on one plant as in Selaginella and some cedars, Juniperus. See also: dimorphism.

annotinal

Appearing yearly.

annual

A plant whose life cycle is of only one year's duration.

annual production

The amount of yield each year by an organism or group.

annual ring

The layer of wood produced by a single year's growth of a woody plant.

annual seasons

The major climatic periods of each year: vernal, estival, autumnal, and hibernal.

annual succession

The routine occurrence of plants and animals in an area during each year, such as spring bulbs being replaced by annual flowering plants, and subsequently replaced by autumn perennial flowering plants.

annual turnover

The total accumulation of living organisms produced in one year for a certain area. See also: biomass.

annuation

The highs and lows from year to year in abundance or performance of organisms caused by differences in environmental conditions such as temperature and moisture.

annular

In the form of a ring.

annular corona

Raised fleshy tissue, usually in a ring, on the corolla around the base of the staminal column but not closely adnate to it.

annulated

Made up of rings.

annulus

1. A ring of cells of the leptosporangium (the sporangium of higher ferns), which causes the sporangium to open and to discharge its spores.

anodynes

Herbal medicines that can counteract pain but are milder than analgesics.

anomalicidal capsule

A dry fruit which dehisces irregularly; a rupturing capsule.

anoxia

Condition resulting from an extreme lack of oxygen, usually resulting in permanent damage.

anoxic

Greatly deficient in oxygen.

antagonism

The depressive effect of one organism upon another, such as certain grasses like timothy hay on the production of alfalfa hay.

antecedent moisture

The degree of liquid which has soaked into the soil at the start of the runoff period.

antemarginal

Inside of, or not extending quite to the margin.

anterior

Away from the stem, midrib, pistil or other organ. On a lipped flower, the bottom lip is anterior, the top lip is posterior. Sometimes the anterior lip is less correctly called inferior or exterior.

antero-lateral

In front and on the sides.

anthelmintics

Herbal medicines that can destroy or expel intestinal worms.

anther

The polliniferous part of a stamen.

anther sac

A pocket-shaped unit containing pollen. In many plants, the anther has two lobes, each with two pollen sacs.

antheridium (pl. antheridia)

In cryptogams, the organ corresponding to an anther that produces male gametes; the male organ on the prothallium.

antheriferous

Anther-bearing; containing anthers.

antheroid

Similar to an anther.

antherozoid

Sperm, male gamete; one of the minute organs developed in an antheridium.

anthesis

The time of expansion of a flower.

anthocarp

A pseudocarp consisting of the true fruit and the base of the perianth.

anthocyanin (adj. anthocyanous)

A blue to purplish-red coloring agent, water soluble.

anthracnose

A fungus that forms grayish/whitish spots on leaves and stems.

anthropic (alt. anthropeic)

Refers to the influences of humankind in contrast to natural influences, such as the introduction of IPM pest controls.

anthropochore (alt. anthropochory)

Dispersal of organisms, such as seeds, as a result of human activity. See also: anemochory.

anthropogenous

Refers to practices of humans, such as cultivation or monoculture.

anthropophilous

Refers to plants which grow near humans and their dwellings, such as dooryard violet, Viola odorata.

anti-

Against, opposed to.

anti-inflammatory

Refers to herbal or other medicines that can ease or neutralize swelling, heat, and pain.

antiallergenic

Refers to herbal medicines that can reduce or relieve allergic reactions.

antiaphrodisiac

Refers to herbal medicines that can reduce sexual desire.

antibiosis

The reaction, often death or sterilization, produced in organisms by an antibiotic.

antibiotic

Substance that slows the growth or multiplication of, or kills, a living organism; usually referring to bacteria.

anticline

A geological structure or arch formed by strata from opposite sides rising upward in a common line. See also: syncline.

anticyclone

An air mass with high atmospheric pressure surrounded by lower pressure areas, in which the circulation of the air is clockwise in the northern hemisphere and counterclockwise in the southern hemisphere.

antifungal

Refers to herbal medicines that can slow the growth or multiplication of fungi, or kill them.

antihistamine

Herbal or other medicines that can neutralize the effect or inhibit production of body histamines.

antimicrobial

Refers to herbal or other medicines that can slow the growth or multiplication of microorganisms, or kill them.

antipetalous (alt. antepetalous)

Opposite the petals.

antique rose

A rose which has been in cultivation since at least before 1900. Often refers specifically to an Old Garden Rose.

antiscorbutics

Refers to herbal medicines that provide Vitamin C.

antisepalous (alt. antesepalous)

Opposite the sepals.

antispasmodics

Refers to herbal medicines that can relieve cramping or spasms.

antitumor

Refers to herbal medicines that can prevent or be effective in removing tumors.

antitussive

Refers to herbal medicines that can prevent or ease coughing.

antiviral

Refers to herbal or other medicines that can slow the growth or multiplication of viruses, or kill them.

antrorse

Pointed forward and upward.

aperiodicity

Irregular occurrence of various phenomena, such as leaves dropping out of season (in summer rather than autumn) due to unexpected climatic changes, i.e., storms, droughts, etc. See also: periodicity.

apetalous

Having no petals.

apex

The top or tip of a structure.

aphids

Small, often wingless insects that suck sap.

aphotic

The deep zone of an ocean or lake receiving too little sunlight to permit photosynthesis.

aphotic zone

The deeper portions of bodies of water in which sunlight does not penetrate with enough intensity to cause changes in organisms. See also: disphotic zone, euphotic zone, photic zone.

aphototropism

The response of an organism in turning away from the source of light. See also: photophobic, photomanic.

aphrodisiac

Refers to herbal preparations that can stimulate sexual desire.

aphyllous

Without leaves.

aphytal zone

The deeper portion of a lake bottom that lacks plants, including the sublittoral zone and the profundal zone.

apical (adj. apically)

1. Borne at the tip of an organ, farthest from the point of attachment, e.g., a bud which terminates a stem. 2. Describes the cells composing the apex of the leaf. They are often broader and shorter than the cells of the middle of the leaf.

apical dominance

The ability of the apical meristem to produce hormones to prevent side shoots or buds from developing while it is growing.

apiculate

Having an apicule.

apicule

A short sharp point, not rigid, found at the tip of a leaf, bract, or petal.

apiculum (adj. apiculate)

A short, pointed, flexible tip.

apo-

A prefix denoting away from or separate.

apocarpous

With carpels separate rather than united. See also: syncarpous.

apogamous

Developed without fertilization.

apogamy

The formation of a sporophyte from a gametophyte by asexual means such as budding, rather than by sexual fertilization.

apogeotropism

The response by an organism of turning away from the earth, e.g., plant stems growing upward.

apomict (adj. apomictic)

A plant that reproduces by apomixis.

apomixis

Reproduction without fertilization or formation of gametes.

apomorphic

Describes a derived characteristic. See also: autoapomorphic, pleisiomorphic, synapomorphic.

apopetalous

With separate petals, not united to other petals; choripetalous.

apophysis

See hypophysis, the more correct term according to Braithwaite.

aposepalous

With separate petals, not united to other petals; chorisepalous.

aposporous

Having the condition of apospory.

apospory

The formation of a gametophyte from a sporophyte by asexual means without meiosis or spore formation.

apothecium (pl. apothecia)

The open fungus fructification, as a cup or disc, lined with asci.

appendage

A structure attached to or arising from a larger structure.

appendiculate

Describes cilia with small transverse spurs attached at intervals along the margin. As these bars sometimes extend inward instead of laterally, they are not always visible in a strictly dorsal view.

appendix

The long narrow development of the spadix in Araceae.

applanate

Pressed; flattened.

appressed

Lying close and flat against, as a bud against a twig.

approximate

Located close together and nearly touching.

apron

A layer of hard material like concrete or timber that protects soil from erosion, e.g., pavement at the spillway of a dam.

apterous

With no wings.

apud

The connector term used between names when two authors describe the same species in separate publications, e.g., Ceratozamia latifolia Miq. apud Tijdschr.

aquaculture

1. The raising of fish or other aquatic animals for their commercial value. 2. Hydroponic horticulture.

aquatic plants (alt. aquatics)

Those species whose seeds germinate in water or in bottom soil of bodies of water, usually with submersed or floating leaf types.

aqueduct

A conduit for water, whether canal, pipe, tunnel or a combination of these or others.

aquiculture

The use of artificial reefs and other structures to increase the production of seafood in fresh or salt water.

aquifer (alt. aquafer)

A natural holding tank of porous rock or soil locked between impermeable layers in which water may travel long distances.

aquiherbosa

Communities of herbaceous plants growing in ponds and marshes.

aquiprata

Communities of plants where the surface water is a necessary factor, as in wet meadows.

arable land

Land that may immediately be used for farming without clearing trees, draining, etc.

arachnoid (adj. arachnose)

A surface with many fine hairs that appears covered with cobwebs.

araneous

Cobwebby.

arbor (alt. arbour)

1. A lattice-covered structure with open sides, usually with vines, such as grapes trained across the top. 2. An orchard or a garden devoted to trees.

arboreal

Of or resembling a tree.

arboreous

1. Having many trees. 2. Tree-like.

arborescent

Tree-like in appearance and size.

arboretum (pl. arboreta)

A botanical center devoted to the study and exhibition of trees.

arboriculture

The cultivation of trees.

arcade

A series of arches with columns or piers; in gardens, usually having trees forming the arched ceiling.

archaeophyte

A plant that existed in prehistoric times.

archegone

The egg cell produced in the archegonium.

archegonium (pl. archegonia, adj. archegonial, adj. archegoniate)

The flask-shaped female reproductive organs on the prothallium in the higher cryptogams corresponding to a pistil in the flowering plants and containing the egg which becomes the sporophyte. See also: antherozoid.

archibenthic zone (adj. archibenthal)

The ocean layers between 200 feet and 3300 feet (65 and 1050 m.)l; the upper part of the abyssal zone.

arching

Curved gently outward and then downward; generally said of stems, large leaves, and floral clusters.

architectural

Describes plants that have very strong shapes and are used in landscapes for this reason.

arctic

Describes an extremely cold climate, particularly that of the polar regions.

arctic-alpine

Refers to areas which are mountainous, above the tree line, and north of the arctic circle.

arcuate

1. Moderately curved. 2. In mosses, refers to a capsule bent in a curve like a bow.

area

The total range in which a taxon or community may be found. See also: basal area, coverage.

areg

A sand desert.

arenaceous

1. Describes a sandy soil. 2. Growing in sandy soil.

arenicolous

Refers to organisms which live where there is sandy subsoil.

areography

The study that deals with the range of a species. See also: area.

areola (pl. areolae)

A space enclosed by anastomosing veinlets.

areolate

Having areolae; marked out into small spaces; reticulate.

areolation

The network formed by the outlines of the cells of a leaf.

areole (adj. areolate)

1. The space between veins of a leaf or a similar partition. 2. A small pit or cavity marked out upon a surface. 3. The area from which hairs, spines, flowers, or branches may arise in Cactaceae.

argillaceous

Like clay, growing in clay, or clay-colored.

arid (n. aridity)

Xeric, extremely dry.

aril

A fleshy appendage growing at or about the hilum of a seed.

arillate

Having an aril.

arista (pl. aristae)

A bristle-like appendage, like the awn of grasses.

aristate (syn. awned)

1. Describes a leaf which terminates in a stiff, bristle-like tip. 2. Awned; provided with stiffish bristle-shaped appendages.

aristulate

Having a small awn.

armature

1. The basic framework of an object or organism. 2. A protective covering or other kind of defense, e.g., thorns.

aromatic

Having a spicy odor, at least when crushed.

aromatics

Refers to herbal medicines that have a pleasing odor and pungent taste.

arrangement

A nontechnical term that refers to the way things are put together, e.g., an inflorescence may be described by the arrangement of the flowers, or leaves can be arranged opposite or alternate.

arrhythmic

Refers to activity which is not dependent upon light or dark. See also: diurnal, nocturnal.

arroyo

A watercourse, gully, or channel carved by water, often dry.

ARS

An acronym representing the name the American Rose Society, a nonprofit, educational organization dedicated to the cultivation and enjoyment of roses.

arthropod

Insect, crab, spider, centipede, or other animal from the phylum Arthropoda.

article

A segment of a jointed stem.

articulate (syn. articulated)

1. Having a swollen area, often discolored, at the node. 2. With a joint, often on a zigzag stem.

artifact

1. A structure or appearance in a tissue due to death or the use of a reagent, and not present during life. 2. A product of human workmanship found on archeological digs.

artificial selection

The intentional human manipulation within a population to produce a desired evolutionary response. See also: natural selection.

artificial stocking

The introduction of animals from another area, such as providing streams with new species of fish or bringing gamebirds into an area where they are scarce.

arundinaceous

Reed-like.

ascending

Rising somewhat obliquely, or curving upward. Ascending ovule: one that is attached above the base of the ovary and is directed upward.

ascogonium

The special hypha from which the fertile hyphae develop to produce asci.

ascomycete

A fungus producing asci.

ascus (pl. asci)

The reproductive cell (meiotangium) of a fungus containing usually eight ascospores.

asepalous

Without sepals.

aseptate

With no partitions or divisions.

asexual

Lacking sexual characteristics as in a sterile ray floret; or when referring to reproduction, occurring without the fusion of egg and sperm.

asexual propagation

The propagation of plants through means other than fertilization, including layering, cuttings, tissue cultures, and the division of clumps.

asexual reproduction

Not involving or requiring fertilization and meiosis.

ashlar

1. Dressed, finely-jointed stonework, usually having a polished surface and sometimes consisting merely of a facing for a wall of rubble or brick. 2. The stones used in this stonework.

aspect

1. The appearance of vegetation during one of the seasons of the year, e.g., the vernal aspect. 2. The direction toward which a slope is facing, e.g., the southern aspect.

aspection

The change in the appearance of vegetation and its visible attributes during the succession of seasons of the year, as budding in prevernal, flowers in vernal, green fruit in estival, ripe fruit in serotinal, and bare branches in hibernal.

asperous

With a rough surface.

asperulate

Somewhat rough to the touch.

asperulous

Refers to a surface with short, hard projections.

assimilation

Cellular conversion of raw materials into structures useful to a plant, such as cell walls and protoplasm.

association complex

A group of associations which occurs in a defined area.

association fragment

A stand of plants that requires other characteristics to meet community standards.

association segregate

A climax community which has changed from the original community, like a mature beech-maple association appearing from a mixed deciduous forest.

association table (syn. synthesis table, syn. stand table)

A list of species that occurs in several stands of an association or community, including data on characteristics such as abundance, cover, vitality, etc.

associes

A temporary community in developmental stage.

assortative breeding (syn. assortative mating)

The pairing of male and female organisms in a manner that involves more than chance, so that the mating of similar parents is encouraged.

assurgent

Ascending.

asterean

Belonging to or similar to plants of the aster family, Compositae.

astomous

In mosses, refers to a capsule without a mouth. Used of capsules which have no regularly dehiscent lid or operculum.

astragaloid

Cubical.

astringent

An herbal preparation that shrinks and firms tissue, particularly the skin.

astylous

Lacking a style.

asymmetrical

Having a different shape on each side of a central axis.

asymptotic population

The maximum size possible to a population under present conditions, no matter how long reproduction is allowed to continue.

atavistic

Reverting to a form found in ancient ancestors.

atmometer

Any instrument for measuring evaporation like a porous sphere or open pan of water.

atoll

A circular coral island or islands surrounding a body of water in the ocean. See also: lagoon.

atrocastaneous

Very dark chestnut in color.

atrophy (adj. atrophied, alt. atrophic)

1. A wasting away from lack of nutrition or use. 2. Arrested development of a part or organ inconsequential to the normal development of a plant or animal.

atropurpureus

Colored deep purple, almost black.

attenuate

A long gradual taper, as at the base or tip of a leaf or flower parts, drawn out into a long point. See also: acute.

atypical

Not normal.

auctoris (alt. auctorum, abr. auct., abr. auctt.)

Used in taxonomy when an author has applied a wrong name, usually beginning with "#non," to contrast it to the true type with the correct author, e.g., Betula platyphylla auct. Non Sukachev, which is in fact a different plant, Betula mandschurica.

auger

A T-shaped tool, like a large corkscrew, used for drilling holes in the soil.

auricle

An ear-shaped appendage.

auriculate

Shaped like an ear.

auriculiform

Having the shape of an ear.

aurieles

Small lobes at the basal angles of the leaf, usually consisting of cells differing in size, shape, or both from those of the main part of the leaf. Properly used only when there is an outward curve in the outline of the leaf at the base, but often used loosely to denote the basal angles of widely decurrent leaves.

auroral

Refers to morning, the crepuscular period, or dawn.

autapomorphic

Describes a derived characteristic unique to a given taxon or monophyletic group. See also: apomorphic, synapomorphic.

autecology

The study of the individual in relation to environmental conditions, or sometimes, members of a species studied collectively in the same way.

author

1. The botanist who discovered and named the new taxon. 2. The name or initial(s) following the taxon name, designating that botanist.

autochore

A species in which some action of the parent plant is the chief force for dissemination, e.g., the mechanical projection of seeds in jewelweed, Impatiens.

autochthonous

1. Describes the original or earliest known inhabitants of a region. 2. Originating in the place where found; indigenous. 3. Originating from within a system, such as organic matter in a stream resulting from photosynthesis by aquatic plants. See also: allochthonous.

autoecious (alt. autocious)

1. Refers to parasites which pass all stages of their life cycle on or within the same host, like certain rust fungus. 2. Having male and female organs on the same plant. See also: heteroecious.

autogamous

Self-fertilizing.

autogamy

Where male parts can fertilize female parts of the same flower through self-fertilzation or hermaphroditism; inbreeding.

autogenic succession

Vegetational progression in which each stage modifies the habitat in such a way that it is replaced by another stage, e.g., pond shoreline herbaceous plants being replaced by shrubs.

autolysis

The digestion of an organism or parts of it by its own enzymes.

autonomic

Refers to processes or activities that are spontaneous, arising from internal causes. See also: autonomous.

autonomous

1. Autonomic. 2. Refers to plants, especially those with chlorophyll, that are capable of turning inorganic materials to organic ones for their nutrition or other use. See also: autotrophic, photosynthesis.

autonym

When an author names a new subspecies or variety, the species is given the same new rank, based on the original type of the species and duplicating the epithet, e.g., when Pinus nigra ssp. larico was designated, Pinus nigra ssp. nigra came into being.

autopolyploid

An organism or cell which contains three or more sets of homologous chromosomes that developed from the same species. See also: amphiploid, allopolyploid.

autotrophic (n. autophyte)

1. Refers to organisms that are capable of processing inorganic materials into organic ones by using energy from outside the organism such as sunshine on chlorophyll. 2. Refers to a body of water that is limited in its supply of organic material to what it is capable of producing within its own borders.

autumnal (syn. fall)

Refers to the season between summer and winter that, in the northern hemisphere, includes the months of September, October, and December. Astronomically speaking, it is the period extending from the September equinox to the December solstice.

auximone

A nonessential organic substance of unknown chemical composition, which produces a known reaction, such as growth of duckweed, Lemna, from an extract of dung.

auxin

One of several hormones occurring in plants which regulates certain aspects of growth. They can be produced synthetically and are sometimes used commercially as herbicides or to promote flowering or other types of plant growth.

auxospore

A cell that restores the original size to the diminishing products of cell division.

auxotelic

Describes an inflorescences, parts of inflorescences or axes that do not end in a flower, and in which growth continues beyond the flowering region, See also: anauxotelic.

available nutrient

The portion of nutrient substances, such as nitrates in the soil, that can be utilized by plants at rates and amounts required for growth.

available water

That portion of water held in soil that may be absorbed into the roots of the plant.

available water-holding capacity

The amount of water in soil that can be absorbed by plants, between the high amount at full saturation or field capacity, and the low amount at the permanent wilting capacity.

avalanche

A large mass of snow, ice, rocks, trees, etc., in swift descent down a mountain or over a precipice.

avalanche cone

All the materials left at the base of a slope following an avalanche.

avalanche wind

Moving air stirred up by an avalanche and often destructive over considerable distances.

avenue

A path or road lined with trees on both sides, usually all of the same type.

average distance

The mathematical statement of the distance between plants calculated by dividing the square root of an area by the density of each species within the area.

avitaminosis

Reduced health from deficiency of vitamins.

awl-shaped

Tapering upward from the base to a slender or rigid point.

awn

A bristle-shaped appendage, especially on grass seeds or grains.

axe

A waist-high tool with a vertical, sharpened, narrow wedge head for cutting wood.

axe-shaped

Dolabriform; describes three-dimensional shapes.

axial

Refers to the main line or trunk of the entire plant, the specific branch, the inflorescence, etc.

axil

The angle formed by a leaf or branch with the stem.

axile

Belonging to, or found in, the axil.

axillary

Situated in an axil.

axis

The main line of growth in a plant or organ, e.g., the stem, from which the other parts such as the leaves and flowers grow.

azonal

Refers to soil that has no well developed profile with horizons, such as glacial deposits, dune sand, alluvium.

B horizon

The soil layer between A and c horizons, in which materials from overlying horizons accumulate from precipitation or suspension.

baccate

Berry-like; pulpy throughout.

bacciform

Berry-shaped.

bacilliform (syn. baculiform)

Rod-shaped.

Bacillus thuringiensis (abr. Bt)

A bacterium which is lethal to some insects and is used as a biological control.

backbulb

A dormant water-storing thickened stem that looks like a bulb, found in Orchidaceae. It grows actively as a pseudobulb the first year, then becomes dormant when the next year's pseudobulb takes over.

backcross (alt. back cross)

1. To cross a first-generation hybrid with one of the parental types. 2. The offspring of a cross between a hybrid and one of its parents.

backfill

Earth used to fill trenches or holes, often the same soil that was removed to make the hole.

backfire

A fire purposely set ahead of an advancing fire to destroy flammable materials, enabling workers to control the main fire.

backflash

Movement of a poison through natural root grafts, from trees that have been treated with poison, back to non-treated trees.

backshore

That part of the beach from the first crest toward the land.

bactericide (alt. bactericidal)

Something, such as an herbal preparation, capable of destroying bacteria.

bacteriophage

A virus which destroys bacteria.

bacteriorhizae

Nodules on the roots of most legumes and a few other plants, which contain bacteria that uses atmospheric nitrogen to synthesize organic compounds.

baculiform (syn. bacilliform)

Rod-shaped.

badlands

Regions of eroded land on which most of the surface is covered with ridges, gullies, and deep channels, having sparse vegetation.

Baermann funnel

A modification of the Berlese funnel, used to force nematodes out of soil or debris by filling the funnel with warm water, driving the nematodes into a vessel below.

baffle-pier

A blockage placed in the path of high-velocity water, like a pier on the apron of an overflow dam.

baffles

Vanes, guides, or other devices inside a conduit to check eddy currents below them, and provide more uniform distribution of sp.ed.

bagasse

Residue of sugarcane after the juice has been extracted.

baguio

A term used in the Philippine Islands for a tropical cyclone or typhoon.

bajada

A term used in the southwestern united States to describe outwash slopes with long straight profiles.

balance of nature (alt. ecological balance, alt. biotic balance, syn. dynamic equilibrium, syn. biotic equilibrium)

A term for an ideal condition in which the interrelationships of organisms to one another and their environment appear harmonious, like a climax forest. In reality, the balance is continually upset by natural events.

balanoid

Refers to barnacles.

bald

A treeless region in forest vegetation; perhaps an area of grasses or shrubs in southern Appalachia, or a mountaintop.

balled and burlapped

Taken out of the ground with a ball of soil around the roots and then wrapped in burlap for support.

balling

A condition where outer petals stick together and fail to open, often occurring in damp weather.

ballistic

Refers to fruits that discharge their seeds forcefully; catapult fruits.

bamboo

Any of various usually woody and/or arborescent grasses of the tropical or temperate regions belonging to the genera Bambusa, Arundinaria, Phyllostachys, Sasa, Dendrocalamus, etc., most having hard, hollow stems.

banados

Shallow swamps in Paraguay.

Bancroft's Law

A generalization that organisms and communities tend toward a state of dynamic equilibrium with the environment.

bank storage

Water absorbed by the bed and banks of a stream, returned in whole or part after ground water level falls.

bar

1. A continually moving deposit of sand forming a ridge along the seashore or the coasts of large lakes. 2. A unit of atmospheric pressure equivalent to 29.53 inches (750.1 mm) of mercury at 32 degrees at latitude 45 degrees.

barachore

A species in which the fruit or seed is desseminated by its own weight, e.g., walnuts, Juglans, falling to the ground. See also: autochore, diaspore.

barbed

Furnished with rigid points or short bristles, usually reflexed like the barb of a fish hook.

barbed trichome

A trichome with terminal or lateral retrorse projections, each projection being a barb.

barbellae

Short, stiff barbs.

barbellate

Finely-barbed.

barbulae

Outgrowths on the margin of the wings or in the throat of the corolla, sometimes with apical hairs or papillae (found in plants of the genus Scaevola.)

barbulate

Finely-bearded.

barchan

A distinctive isolated, crescent-shaped, sand dune with the ends projecting on the side opposite that from which the wind blows, common in Turkestan.

bare-root

Describes a plant that is prepared for transporting by removing all the soil around its roots.

bark

The outer covering of the trunks or branches of trees and shrubs.

bark-cambium

The layer of cells that produces new bark.

barogram

A continuous record of the readings of a barograph.

barograph

A self-registering barometer.

barotaxis

Response of an organism in response to barometric stimulus.

barotropism

Change of position of a plant or sedentary animal in response to a barometric stimulus.

barrens

A region where vegetation is absent or poorly developed.

barrier

1. Any feature or condition that restricts movement of organisms or prevents establishment of organisms which have migrated there. 2. A condition that prevents or significantly reduces crossbreeding of organisms.

barrier beach

A strip of land built up by the action of waves, currents and winds, and which protects inner areas.

basal (alt. basilar)

1. Growing from the base of a stem; used in reference to leaves at the base of the stem. 2. One of the main canes of a rose bush, originating from the bud union. 3. Describes cells at the base or insertion of the leaf, often of different shapes and colors from those of the main part of the leaf.

basal area (alt. basal cover, alt. ground cover, alt. cover)

1. The area of the cross section of a tree at a height of 4.5 feet above the ground, generally written as the total of the basal area of the trees in a forest in square feet per acre. 2. The surface of the soil actually covered by a plant, as compared to the full spread of the herbage, which in grassland ecology often measures at one inch above the ground.

base

The proximal portion of a structure; that part nearest the point of attachment.

base exchange capacity

A measure of the absorptive capacity of a soil for materials with exchangeable cations, a nonacid reaction. A soil with a high base exchange capacity will retain more plant nutrients and is less apt to leach than one with a low exchange capacity.

base flow

Springs; stream flow coming from subterranean sources in contrast to surface runoff.

base level

The lowest level to which a land surface can drop by action of water; the permanent base level is sea level.

base saturation

The proportion of the base exchange capacity that is saturated with metallic cations.

basidiomycete

A fungus-producing basidia.

basidium (pl. basidia)

The reproductive fungus cell (meiotangium) producing usually four spores on the outside.

basifixed

Attached by the base.

basin irrigation

An artificial method of watering plants in which a level field is surrounded by a ridge of earth so that a shallow body of water may accumulate before it soaks into the soil.

basin listing

A way of working land by constructing small dams at intervals across furrows to form basins for collecting rainwater, slowing runoff and erosion.

basionym

A specific or infraspecific name which has priority over other names later given to the same plant by different authors. See also: synonym, homonym, tautonym, autonym.

basipetal (adj. basipetalous)

Developing from the apex towards the base. See also: acropetal.

basiscopic

Facing the base of the axis on which it is borne.

basitonic

Describes flowering seasonal shoots which produce no leaves (except for bracts in some cases) below the inflorescence. See also: acrotonic.

basophilous

Refers to organisms which have adapted for life in alkaline soil or other medium.

bast

The fibrous portion of the inner bark.

bathyal zone (adj. bathyic)

The deep part of the ocean where light does not penetrate sufficiently for normal plant growth.

bathypelagic

Refers to deep parts of the ocean, but not including the ocean bottom.

bathyphyll

A modified leaf which attaches a plant to a substrate.

bathysphere

A pressure-resistant underwater structure with a spherical chamber in which scientists can descend deep into the ocean.

batten

Lath, often wired together as in snow fencing.

batten stripping

Plastic strapping which can be used in a manner similar to snow fencing.

bay (alt. embayment)

A notch in the shoreline, not restricted to any single form. It may be a lobe of water extending inland as deeply as a firth or fiord, or it may be as shallow as a quarter moon shape. See also: cove.

bayou

A creek or slow-moving stream.

beach

Where water meets land at the edge of lakes, oceans, etc. A barrier beach is a ridge of sandy deposits separated from the mainland by a section of water. See also: atoll.

beach pool

The barrier beach pool is a shallow lagoon formed inland from the barrier beach. 2. A sand spit beach pool is a shallow lagoon, generally S-shaped, that is inland from a sand spit, most often on the protected side of a headland.

beak

Prolonged narrow tip of the operculum.

beaked

Ending in a prolonged tip.

bearded

Bearing a long awn, or furnished with long or stiff hairs, as seen on the lower petals of some irises.

Beaufort scale

An artificial number scale invented by Francis Beaufort in 1805 to show approximate wind sp.ed ranging from 0 miles per hour (mph) for calm to 12 mph for a hurricane velocity in excess of 75 mph.

Beckmann thermometer

A thermometer for a narrow range at very accurate readings, such as one graduated to 0.01 degrees for a range of 7 degrees.

bed load

Rocks, sand, gravel, and other debris rolled along the bottom of a stream by high-velocity water, in contrast to silt load, which is suspended in place.

bed preparation

Mixing compost, ashes, and/or sand with natural soil to improve growing potential.

bedding plants

Plants used in large numbers in usually temporary displays. Most often annuals, tender perennials, and bulbs not able or intended to naturalize and which are grown indoors or under glass before planting.

bedrock

The layer of solid rock underlying a soil profile or other surface materials.

belly plants

A humorous term for inconspicuous plants, which often require botanists to crawl on their bellies to find them.

below

Refers to the position of one portion of an organ or plant in relation to another portion; the part "below" is the nearest to the attachment. See also: above.

belt

A long narrow area or strip of vegetation with characteristics which define it from adjoining areas.

belt transect

A type of vegetational analysis in which a portion of land a few inches or a few feet wide, and often a meter wide and 10 to 100 meters long, has constituent plants recorded.

bench mark

The point of reference in elevation surveys from where surveyors start to furnish an accurate survey.

bench terrace

A shelf-like embankment of earth, usually man-made, along a contour of sloping land to control runoff and erosion. See also: ridge terrace.

benthic

Refers to the bottom of any body of water, regardless of depth. Oceanic benthic division is composed of littoral, sublittoral, archibenthic, and abyssal-benthic zones.

benthos

Organisms which live on or at the bottom of oceans or fresh water, from the water's edge down to the deepest water depths. See also: nekton.

bentonite

Absorptive and colloidal clay used as a sealing agent, as in lining ponds.

Berlese funnel

A device in which soil is placed, and heat and light are applied from above, forcing mites, collembolons, etc., into a container below it. See also: Baermann funnel, Tullgren funnel.

berm (alt. berme)

1. A narrow shelf, path, or ledge typically at the top or bottom of an escarpment or beside a road. 2. A mound or wall of earth.

berry (pl. berries)

A fleshy fruit that contains small seeds, the whole pericarp of which is fleshy or pulpy.

betacyanin

The nitrogen-based red pigments of beets, Beta spp., and other Chenopodiaceae, as well as flowers of Cactaceae, Portulacaceae, and others.

biannual

Occurring twice a year. See also: biennial.

biauriculate

Having two auricles.

biblical garden

A botanical area consisting of plants mentioned in the Bible.

bibracteolate

Having two bracteoles.

bicalcarate

Having two spurs.

bicallose

Having two callosities.

bicarinate

Having two keels.

bicarpellate

Having a two-celled fruit.

bicentric

Refers to a taxon which has two centers of dissemination or evolution.

bicolored (alt. bicolorous)

Having two colors on the same structure, often said of petals.

biconvex

Bulging outward on both sides, almost a sphere or orb.

bicornute

Having two horns.

bicostate

In mosses, having a double costa, which is usually much shorter than in leaves having a single costa.

bicrenate

Biserrate with both sets of teeth being shallow and rounded.

bidentate

Having two teeth.

biennial

A plant with a life cycle that is completed in two years or seasons, with the second season usually devoted to flowering and fruiting.

bifacial

Refers to leaves with distinct adaxial and abaxial surfaces.

bifarious

Growing in two ranks, such as needle-type leaves growing in two rows on opposite sides of a twig; distichous.

bifid

1. Cleft into two parts. 2. Divided into pinnae-bearing pinnules.

biflorus

Refers to a plant which flowers in both spring and autumn.

bifoliate

Having just two leaves.

bifoliolate

Having just two leaflets per leaf.

bifurcated

Forked or divided into two parts.

bigeminate

In two pairs; used in describing pinnate leaves which have only two pairs of pinnae.

bigeneric

A hybrid produced by crossing parents from two genera.

bilabiate

Two-lipped.

bilamellate

Made up of two plates.

bilateral symmetry

Describes flowers that can be divided into two equal halves by only one line through the middle.

bilocular

Two-celled.

binary fission

The division of a single-celled organism into two daughter cells.

binate

Growing in pairs.

binder

Hardened cement paste.

binder twine

Coarse jute or plastic cord for baling hay or tying bundles of wheat or other grain. See also: nursery jute.

binomial (syn. binary name, syn. binary combination)

A name consisting of two parts, the first being the genus and capitalized, the second being the species and usually lowercased initial with both names being italicized, e.g., Gypsophila elegans.

binomial nomenclature

The use of the genus and species names together to identify a given organism in the taxonomic system.

bioassay

Determination of relative strength of a substance by testing on an organism.

biocenose (alt. biocoenose, alt. biocoenosis)

All of the interacting organisms living together in specific habitat, usually containing producer, consumer, reducer, and transformer types. See also: ecosystem, community, association.

biochemical oxygen demand (abr. B.O.D.)

A test to detect and measure pollution in water by determining the quantity of oxygen already used up by oxidizable materials.

biochore

A subdivision of the biocycle which contains a group of biotopes which resemble one another; habitat. Examples are grassland, forest and desert.

bioclimate

Microclimate.

bioclimatic law (syn. Hopkins' law)

The generalization that in temperate North America, weather-related events, such as bloom time, can be determined to be similar as you move up or down a mountain 400 feet, or one degree of latitude, or 5 degrees of longitude. In the spring, each of these measurements are eastward or upward and are four days later; in autumn, they are westward or downward and are four days earlier.

bioclimatology

The study of interrelationships between living things and the climate.

biocoenology (alt. biocoenotics)

The study of communities including qualitative and quantitative analyses.

biocycle

A subdivision of the biosphere, including saltwater, freshwater and land. Each consists of biochores. See also: biotope.

biodemography

Numerical and mathematical treatment of population problems.

biodiversity

The totality of genes, species, and ecosystems in a specified area, or the entire world.

biodynamic

Relating to a system of farming that uses only organic materials.

bioecology

A branch of biology treating interrelationships of both plants and animals among themselves and with their environment. See also: ecology.

biogenesis (adj. biogenic)

The principle that plants or animals can originate only from other plants or animals. See also: spontaneous generation.

biogeocenose

A specific ecosystem unique to a designated geographic area.

biogeochemical cycle

The circulation of chemical elements (e.g., oxygen, carbon, etc.) from the environment into plants and animals and back again into the environment.

biogeographic region

A biome.

biogeography

The branch of biology that treats the latitude and longitude of the location of plants and animals; range. See also: chorology.

biointization

The chemical treatment of seeds to stimulate growth.

biological clock

The rhythmic repetition of processes in organisms, like the need for sleep in mammals.

biological control

The use of living things to control pests, such as the control of aphids by lady beetles; integrated pest management.

biological efficiency

The ratio of the productivity of an organism or community of organisms to that of its supply of energy. A black bear would have a much higher efficiency hunting in the summer than in winter, so it is more efficient to hibernate during the winter months.

biological equilibrium (syn. biotic balance, syn. balance of nature)

The state of natural control, self-regulation of the numbers of plants and animals in a community, brought about by interactions within and between plants and animals and the effects of environment such as weather. For example, as the numbers of white-footed mice, Paramyscus, rise, grass seeds, Graminae, decrease and the numbers of foxes, Vulpes, increase. See also: life cycle, pyramid of numbers.

biological factor

An influence that results from biological agents, including biotic factors such as lack of sunshine and physiologic factors like hormones. For example, death rates of white-tailed deer, Odocoilus, increase along highways during rutting season at night.

biological race (syn. biological strain)

A group of organisms which differ only in their physiological or ecological behavior from other groups in the same species, e.g., woodland white-footed mice, Paramyscus, run in straight lines where meadow white-footed mice run zigzag lines.

biological resources (syn. biotic resources)

The factors of biodiversity which are of direct, indirect, or potential use to humanity.

biological spectrum

A percentile tabulation of the plants of a community into the life form classes according to Raunkiaer's classification.

biologics

Biological products such as vaccines.

biology

The study of living organisms.

bioluminescence (syn. phosphorescence)

The emission of light by living organisms such as fireflies and jellyfish.

biomass

The total mass of all living organisms in a given area.

biome (syn. biotic formation)

The ecology of a particular habitat, characterized by its unique plant and animal symbiotic relationships, and maintained by local climatic conditions.

biome-type (syn. biorealm)

A group of similar biomes, such as the temperate deciduous biome-type which includes all the deciduous forests of eastern North America, China and Manchuria, and Europe.

biometry

The statistical study of organisms.

bionomics

The study of the relationship of organisms to each other and their environment. See also: ecology.

bioregion

An area defined by social, biological, and geographic criteria, rather than geopolitical jurisdictions.

bioregional management (syn. bioregional planning)

Directional supervision over an area of similar habitat rather than by standard state/county lines, e.g., cooperative public, private, and business environmental planning for a major watershed such as Chesapeake bay.

bios

Plant and animal life.

bioseston

All living components of the seston.

biosphere

That part of the earth and its atmosphere that can support life.

biosynthetic (n. biosynthesis)

Describes a chemical compound produced by a living organism.

biosystem

Ecosystem.

biosystematics

The classification of living organisms that recognizes and differentiates biotic units into taxa on the basis of genetic relationships.

biota (syn. flora and fauna)

All of the living things, including animals, plants, fungi, and microorganisms, located in a given area.

biotechnology

Applied biological science, especially in genetic engineering and DNA technology.

biotic

Refers to any aspect of life, but especially to characteristics of entire populations or ecosystems.

biotic area (syn. biotic region)

A general term delineating any large area from adjacent areas on the basis of the composition of its biota.

biotic climax

The type of community capable of lasting for long periods of time under the present soil and climate conditions, in combination with the animals living there, including humans. See also: edaphic climax, physiographic climax, sere.

biotic environment

All living things found in the environment of an organism or community.

biotic factor (syn. biological factor, syn. biotic influence)

Environmental influences caused by plants or animals like shading or trampling. Sometimes used so nonliving effects are included, like landslides. See also: coaction.

biotic potential (syn. reproductive potential, syn. breeding potential)

The natural capacity of an organism to survive and reproduce, which is slowed or controlled by environmental resistance.

biotic pressure

The tendency of a species or community to extend its range.

biotic province

A major ecological section of a continent containing one or more regional communities of plants and animals. See also: biome, formation.

biotin

1. A substance which promotes or stimulates growth and repair. 2. One member of the Vitamin B complex.

biotope

A region environmentally uniform in conditions and in the flora and fauna which live there.

biotrophic

Describes an organism which cannot survive or reproduce unless it is on another organism.

biotype

1. A group of organisms sharing a genotype. 2. A particular physical characteristic distinguishing a population of an organism adapted to a particular environment which does not occur in populations of the same species in other environments.

biovulvate

Having two ovules.

bipartite

Divided into two parts almost to the base.

bipinnate

Twice pinnate; the primary leaflets being again divided into secondary leaflets. See also: bipinnatifid.

bipinnatifid

Twice pinnatifid. See also: bipinnate.

bipinnatisect (alt. 2-pinnatisect)

Refers to a pinnately compound leaf, in which each leaflet is again divided into pinnae.

bipolar distribution

Refers to a taxon present in both the northern and southern hemispheres with no apparent connection between populations.

Birge's rule

A generalization theorizing that the thermocline is the transition layer in lakes in which the temperature decreases at a rate of one or more degrees for each meter in depth.

bisect

A line transect which shows the vertical and lateral distribution of roots at the walls of a trench with the above-ground parts of plants along the verge.

bisected

Completely divided into two parts.

biseptate

Having two partitions.

biseriate

Arranged in two rows.

biserrate

Refers to a serrate border where the principal teeth are serrated.

bisexual

A flower having both stamens and pistils. See also: synoicous.

bistratose

Having two layers of cells.

biternate

Twice ternate; with three pinnae each divided into three pinnules.

bitten

Praemorose, with ragged edges as though chewed.

bivalent

A pair of chromosomes, usually one from each parent.

bivalvular (alt. bivalvate)

With two valves.

bivoltine

Refers to organisms which produce two generations each year, like raspberries, Rubus, which produce fruit in late spring and fall.

black alkaline

Soil with a pH well over 7.5, covered with a dark crust of sodium or potassium carbonates.

black spot (alt. blackspot)

A fungus appearing as large, fuzzy black spots on rose leaves, especially in wet weather.

blacktop

Asphalt surfacing used for driveways, paths, and roads.

bladdery (alt. bladder-like)

Inflated, with thin walls like the bladder of an animal.

blade

The expanded portion of a leaf, frond, etc.

blanching

Excluding light from the green parts of plants so that they become white and tender; etiolated.

blast

Injury caused by disease or conditions such as hot winds that shrivel buds, branches, etc.

bleed

To have water seep to the surface of cement paste due to settling.

blend

Two or more colors which gradually merge but are distinguishable from a distance of six feet (used in describing dahlias.)

blight

1. A disease of plants resulting in withering, cessation of growth, and death of parts, especially young tissue. 2. An organism that causes blight, such as a bacterium, fungus, or virus.

blistered

Where the surface of an organ is puckered, the veins being tighter allowing the tissue to round up.

blizzard

A storm in which high winds drive fine snow and ice crystals, reducing visibility.

bloom

1. A flower or blossom. 2. A whitish, powdery, or waxy covering.

blossom

The flower, often applied to fruit trees.

blown

1. Past tense of to blossom; already opened, as in a full-blown rose. 2. No longer viable, perhaps from drought or disease, as "blown buds of barren flowers."

blowout

A wind-blown excavation in loose soil.

blunt

Not pointed.

bob-back

To severely dehorn or damage woody plants while attempting to prune, without understanding the process.

bog (adj. boggy)

1. An area of little or no drainage acidified by rotting vegetation, often with some open water surrounded by a floating mat of sedges, ericaceous shrubs, acidophilous species, and sphagnum mosses. A quagmire, which trembles or gives way underfoot. 2. Loosely, and not technically correct, a marsh, swamp, moor, fen, muskeg, or heath.

bog soil

A mucky or peaty surface horizon with a peat underlayment.

bole

1. The trunk of a tree below the first major branch. 2. The crisscrossed bases of palm leaves.

bolson

A depression lacking above-ground drainage in an arid or semiarid region, a term primarily used in Mexico and southwestern U.S.

bolt

To produce flowers and seeds prematurely.

bomb

A pressurized can of insecticide or other compound.

bonitation (alt. ecological bonitation)

The state of well being in a population, reflected by increasing numbers of individuals.

bonsai

1. The art of growing miniaturized trees or shrubs trained for aesthetic effect. 2. A plant grown in such a way.

bonsai scissors

A cutting tool with large handles and small, very sharp, blades.

bool and clay

A rough form of masonry using locally available, uncut stone and clay mortar.

border dike

Man-made ridges of earth to hold irrigation water within certain limits in a field.

border fork

A heavily-constructed garden tool that is shaped like a fork with round tines and is used for digging in garden borders and flower beds.

border irrigation

Flooding fields by the use of border dikes.

border strip

A demarcation surrounding a plot, usually given the same treatment as the plot.

bordered

Having a margin different from the rest of the leaf.

bore

A tidal wave with a forward wall of water three feet (one meter) or more in height, advancing upstream in a narrow river estuary.

boreal forest

A forest made up mostly of conifers, such as that reaching across North America from Newfoundland to Alaska.

boreal period

The climatic period from about 7500 to 5500 B.C., typified by warm dry conditions.

borer

An insect larva that tunnels into stems and trunks of shrubs, trees, etc.

bosket (alt. bosquet)

A small park or block of woodland with pathways, usually planted with small, understory trees, and often having statuary and waterworks.

bossed

With a conical protrubence rising from the center of a surface, like the bump on a scale of a pine cone.

bostryx (pl. bostryces)

A one-sided helicoid cyme.

botanical

Of or relating to plants or botany.

botanical garden (alt. botanic garden)

A garden devoted to the culture, study, and exhibition of plants.

botany

1. The scientific study of plant life. 2. A botanical treatise or study.

botrytis

A group of fungi that causes plant diseases. 2. The disease caused by such fungi.

bottom deposits

Those materials composing and overlaying the original basin or channel floor of a waterway.

bottom water

To pour water into a saucer underneath a container of a houseplant or jardiniere, allowing the soil to absorb the amount needed. This is often done on plants whose leaves are harmed by water spots, such as African violets, Saintpaulia spp. Generally any excess is poured off after an hour.

bottomland

Flood plain; rich deposits of loam left from flood water runoff.

botuliform

Sausage-shaped.

boulder clay

Unstratified intermix of clay and stones deposited by glaciers. See also: till, drift.

bouquet

1. Flowers picked and arranged in a bunch. 2. A distinctive fragrance.

brachyblast

A short branch or shoot.

brachypterous

Refers to organisms with short wings.

brackish

1. Somewhat salty, as water in saline soils or at the union of a river with the ocean. 2. Less correctly, nonsaline water that is distasteful or nauseous because it is stagnant, etc.

bract

1. A more or less modified leaf subtending a flower or belonging to an inflorescence, or sometimes cauline. 2. The similar structure in cryptogams surrounding reproductive organs.

bracteal

Of or pertaining to the bracts.

bracteate

Having bracts.

bracteolate

Having bractlets.

bracteose

With numerous or conspicuous bracts.

bractlet (syn. bracteole)

A secondary bract, as one upon the pedicel of a flower.

brambles

Plants of the genus Rubus, Rosaceae family, usually prickly and bearing fruit, e.g., raspberries and blackberries.

bran

The edible broken seed coats of cereal grain, often separated from the flour or meal by sifting.

branch

A secondary woody stem growing off of the trunk or main stem of a woody plant.

branchlet

Except for the twig, the youngest and smallest division of a branch.

breccia

Rock composed of angular, often crystalline, pieces in a matrix.

breeder

A person who applies genetics and other sciences in the orderly practice of improving a taxon.

bristle (adj. bristly)

A hair-like prickle.

broad base terrace

An embankment built to carry runoff water along a contour, usually with a rounded crown 15 to 30 feet (5 to 10 meters) wide, with gently sloping sides and a dished channel along the top.

broad-leafed (alt. broad-leaved)

Refers to a plant which does not have coniferous needles or grass-like leaves.

broadcast seeding

Sowing across large areas by scattering seed mechanically or by hand.

broadleaf (alt. broad-leaved)

Having broad leaves, rather than needle-like or scale-like ones.

broadleaf evergreen (alt. broad-leaved evergreen)

An evergreen plant that is not a conifer.

brochidodromous

Describes leaves with pinnate venation in which the secondary veins do not terminate at the margins but rather are joined in a series of prominent arches. See also: acrodromous, eucamptodromous, semicraspedodromous.

bromeliad

Any of the mostly epiphytic herbaceous plants of the family Bromeliaceae found primarily in the tropical and subtropical regions of the Americas, including the pineapple and Spanish moss.

broom-like

Having many parallel branches.

brown earth

1. Any of a group of intrazonal soils developed under deciduous forests. 2. Soils needing replanting or restoration, especially damaged wetlands.

brown forest soils

Those soils with dark brown surface horizons, but becoming lighter-colored beneath. They are rich in humus and are neutral to slightly acidic in composition, commonly appearing under deciduous forests that are quite rich in calcium or other bases. See also: brown soils.

brown podzolic soils

Those soils with thin layers of partly decayed leaves over a gray-brown layer of mineral matter and humus that covers yellow or yellow-brown acid B horizons. These appear under deciduous or mixed forests in cool, humid, temperate regions.

brown soils

Those soils with brown surface horizon, becoming lighter in color with depth. Calcium carbonate appears at one to three feet. These develop under grasslands and shrubs in temperate to cool semiarid climates. See also: brown forest soils.

Brownian movement (alt. Brownian motion)

A condition discovered by Scottish botanist, Dr. Robert Brown (1773-1858), in which rapid vibratory movement of microscopic particles holds the particles and others suspended in a fluid. See also: colloid.

browse

1. Food for livestock or wild members of the extended deer family, Cervidae, consisting of woody twigs and shoots, with or without leaves. 2. To feed on those plants.

browse line

A condition found in forests or brushland with an over population of browse animals like deer or goats, all branches and twigs eaten as high as the animals can reach.

brush

1. A thicket of shrubs, small trees, etc. 2. Branches lopped off trees.

brush matting

1. A covering of branches spread on eroded land to conserve water and lessen erosion that helps establishes trees and other permanent vegetation. 2. A covering of mesh wire along streambanks that holds brush in place to retard erosion.

brush pasture

An area with a natural cover of woody plants, set aside for foraging by goats or other animal browsers.

brushland

An area with shrubs and little other vegetation.

bryophyte

A plant in the botanical division Bryophyta, which includes mosses and liverworts.

bud

The rudimentary state of a stem or branch; an unexpanded flower.

bud eye

A dormant bud in the axil of a leaf, used to propagate through bud-grafting.

bud union (alt. budding union)

The junction on a stem, usually swollen, where a graft bud has joined the stock following the process of budding. Usually found at or near soil level.

bud-scale

A modified leaf, without lamina, protecting a bud.

budded

Grown from a bud grafted onto a desirable understock.

budding (n. bud graft)

Method of propagating woody plants. A cutting of one variety, called the scion, with bud(s) attached is joined onto another related species or variety, called the stock. As the tissues grow together a single plant is formed with top-growth of the scion on the base of the stock.

buffalo wallow

An area in a grassland where large grazing animals have rolled, usually because of biting flies, killing the grass and losing soil.

buffer species

A plant or animal which may serve as an alternate food supply for a consumer animal, lessening the demand for a more desirable food species.

buffer strip

A transect of grassland or other erosion resistant vegetation located between or below cultivated lengths or fields.

buffer zone

1. A strip that partially or fully encloses a study area or other designated area to protect the inner section from ecological disturbance by outside pressures; a transition zone between districts managed for different objectives, such as a wildlife preserve and a state hunting area.

buffering

Modification of environmental conditions by planting vegetation or changing topographic features. See also: reaction.

bulb

A short underground stem with fleshy scales or coats.

bulbate

Inflated.

bulbiferous

Bearing bulbs or bulblets.

bulbil (alt. bulbel, alt. bulblet)

A small bulb or bulb-shaped body, especially one borne upon the stem, and usually produced for asexual reproduction.

bulbous

Having the character of a bulb.

bulk density

The mass or weight of oven dried soil at 100 to 110 degrees Centigrade, per unit of bulk volume, including air space.

bullate

Blistered or puckered.

bunch grass

A style of grass that grows in tufts.

bundle cluster

A cluster such as that of pine needles.

bundle scars

Tiny, somewhat circular dots within the leaf scar, caused by the breaking of the fibrovascular bundles which run through the petioles into the blades of the leaves.

bundle sheath

A clasping collar surrounding a collection of similar parts such as the collar on pine needles.

bur (alt. burr)

A rough, prickly husk covering the fruit or seeds, such as the husk on a chestnut.

buried soil

One or more layers of soil, formerly at the surface, which have been covered by ash, sand, or other deposition.

burl

A deformed outgrowth on the trunk of a tree, often half a hemisphere in form, valued for the unusual wood grain; also the veneer made of such growths.

burn

1. Scottish word for brook. 2. The controlled process of removing dangerous buildups of combustible materials and destroying weed seeds, etc.

burn scar

A scar on a tree trunk left when tissues were damaged by fire. It may later be covered by new tissue.

bursicle

A pouch-like receptacle.

bush

1. A shrub, especially one that is low and thick with many stems rather than a single trunk. 2. A tree- or shrub-covered area in Australia or South Africa, or any uncleared land. 3. Sugar bush is a maple forest where sap is collected to make maple syrup or candy.

butte

A term from the western united States meaning an isolated hill with steep sides and a relatively flat top that is smaller than a mesa.

button center

A round center in a rose blossom, formed by unexpanded petaloids in very double roses.

buttress

1. A flange of tissue protruding from the trunk of a tree, tapering outward at the base. 2. A projecting structure of masonry or wood for supporting or giving stability to a wall or building.

c horizon

In soils, the partly weathered rock fragments which are the parent materials for the upper A horizon and B horizon. This is occasionally lacking. See also: D horizon.

caatinga

The area of northeastern Brazil covered with thorn scrub.

cabling

Connecting tree limbs with steel cable to alleviate ice storm damage.

cactiform

With succulent stems similar to Cactaceae.

cactoid

Resembling a cactus.

cactus (pl. cacti)

A member of the family Cactaceae, having succulent stems and branches with scales or spines instead of leaves and found primarily in arid regions.

caducous

Falling off very early, usually applied to flower parts.

caingin clearing

A term used in southeast Asia for an area which has been cleared so that it can be used for farming.

cairn

Piled stones used as a landmark or memorial.

calcarate

Produced into or having a spur.

calcareous

Containing calcium or calcium carbonate (lime), as an alkaline soil.

calcareous ooze

Partially decomposed organic matter mixed with a quantity of calcareous material on the bottom of some bodies of water.

calcicole

A plant adapted to growing on limestone or alkaline soil.

calcification

A soil process where the surface soil is combined with calcium by the decomposition of plants, especially if a calcareous layer is formed. See also: podzolization.

calcifuge

A plant that does not grow well in lime or alkaline soil.

calcination

Decomposition due to the loss of bound water and carbon dioxide.

calcine

Like a calyx, or belonging to the calyx.

calciphile

A plant that must have lime or alkaline soil.

calciphobe

A plant preferring alkaline soils; an acidophilous plant.

caldera

A large crater formed by the collapse of the central part of a volcanic cone.

caliche

1. A crumbly crust of calcium carbonate formed on a stony base in arid climates. 2. A term used in Chile and Peru for deposits of sodium nitrate.

calicole

A plant living on chalky or limy soils.

caliper

1. An instrument used to measure the diameter of a tree, or other object. 2. The measurement thus attained, usually at breast height.

calli

Small outgrowths on the throat of the corolla of some plants, often acting as tactile guides for pollinators.

callosity

A hardened thickening.

callus (adj. callose)

1. A hard protuberance or callosity, sometimes resulting from a wound. 2. In the grasses, the tough often hairy swelling at the base or insertion of the lemma.

calmative

An herbal medicine that contains a mild sedative or has a calming effect.

Calvin cycle

The cycle of dark reactions of photosynthesis that occurs in the chloroplasts and involves the fixation of carbon dioxide and the formation of a six-carbon sugar.

calycine

Refers to a part of the calyx, or something that is like a calyx.

calycle (alt. calyculus)

The epicalyx, a second calyx or involucre beneath the true calyx.

calyculate

Having bracts around the calyx or involucre imitating an outer calyx.

calyptra

A lid or hood. In mosses, the thin veil or hood covering the mouth of the capsule.

calyptrate

Having a calyptra.

calyx

The outer part (perianth) of the flower, usually green and formed of several divisions called sepals, that protects the bud.

calyx bract

A bract which takes the form of a petal or sepal.

calyx lobe

The portion of the sepal which is apical, or remains free, in a fused calyx.

calyx tube (alt. calyx-tube)

A tube formed partly by the united bases of the sepals and partly by the receptacle. See also: hypanthium.

cambium

The internal layer of living cells between the inner bark and the sapwood where growth takes place that produces secondary xylem and phloem.

Cambrian

1. The oldest geological period in the Paleozoic era, about 500 million years ago. 2. Refers to organisms formed during that period.

campanile

A bell tower, usually freestanding.

campanulate

Bell-shaped; cup-shaped with a broad base.

campestral

Growing in fields.

campo cerrado

A Brazilian type of parkland composed of scattered trees in dense grass.

campos

Grassland located south of the equator in Brazil.

camptodromous

A pattern of venation where the secondary veins curve toward the margin without forming loops.

campylotropous

Describes an ovule or seed so curved as to bring the apex and base nearly together.

canaliculate (syn. tubulose)

Longitudinally channeled or grooved, especially on leaf stalks and midribs.

cancellate

A surface having the appearance of a lattice, with regularly arranged openings, e.g., the endostome of the Fontinalacae.

candle

The tender spring growth of the pine and some other needle-leaf evergreen species.

cane

A long, often supple, woody stem.

canescent

Hoary with gray pubescence.

canker

A patch of dead cells on a trunk or branches of a woody plant.

cano-tomentose

Density of hairs midway between canescent and tomentose.

canopy

The uppermost layer of branches and foliage of forest or a single tree.

canopy layer

The highest stratum of growth in a forest, where the trees form almost solid treetop canopies.

canopy trees

Forest trees which have reached a size where the crown becomes part of the uppermost layer.

cant hook

A term used in the united States for a tool used for rolling logs, consisting of a wooden lever with a moveable iron hook near the end, often with a lipped iron ring round the tip. See also: log lifter, peavey.

capability (alt. land capability)

A measurement of the suitability of land for some particular use without permanent damage to the land.

capacity formula

Mathematical rule used in hydraulics to calculate the extent or discharge volume of a channel.

capillary

Hair-like.

capillary action (syn. capillarity)

The phenomenon of a liquid spontaneously seeping up thin tubes due to adhesive and cohesive forces and surface tension.

capillary porosity

The aggregate volume of small pores within a particular soil to retain water against the force of gravity.

capillary water

The part of soil water which is held cohesively as a continuous layer around particles and in spaces, most of it being available to plant roots.

capitate (syn. capitiform, alt. capitose)

1. Shaped like a head; collected into a head or dense cluster. 2. Terminated by a bulbous, swollen area.

capitellate

1. Shaped like a tiny head. 2. Clustered in a compact headlike grouping.

capitulum

A dense inflorescence of unstalked flowers shaped like a globe, such as a buttonbush, Cephalanthus; or sometimes shaped flat, as in Compositae.

caprification

The commercial process of pollination of fig plants by wasps.

capsid bugs

Green or brown bugs that suck sap of young growth, causing distortion of flowers and leaves.

capsular

Belonging to or of the nature of a capsule.

capsule

1. A dry dehiscent fruit composed of more than one carpel that splits partly open at maturity. 2. The enlarged distal end of the sporophyte; it contains the spores, and is sometimes known as the sporangium.

carapace

The hard case or shield covering part of the body of animals like turtles and some invertebrates.

carbohydrates

Neutral compounds of carbon, hydrogen and oxygen formed by green plants, including sugars, starches and cellulose.

carbon

Nonmetallic element found in all organic compounds.

carbon 14 dating

The selection and testing of undisturbed soils, buried materials such as wood, firepit remains, and other organic materials, for measurement of radioactive carbon 14 with a half-life of approximately 5,500 years, to determine the rough age of the selected materials.

carbon assimilation

Photosynthesis.

carbon cycle

The process of changing atmospheric carbon into sugar by photosynthesis in plants, synthesis of more complex organic compounds in higher plants and animals, and the return to carbon dioxide by respiration or death and decay of plant and animal tissues.

carbonate zone

A soil layer with concentrated carbonates, chiefly calcium carbonate, found most often in arid areas.

Carboniferous

Refers to the Pennsylvanian (upper carboniferous) and Mississippian (lower carboniferous) geological periods in the upper part of the Paleozoic era, about 200 to 260 million years ago.

carcinogen (adj. carcinogenic)

Substance capable of producing or inciting cancer.

cardinal points

The four chief directions of a compass reading: north, south, east, and west.

cardioactive

Herbal medicines that can affect the heart.

carina

Keel.

carinal

On or relating to a ridge or keel.

carinate

Having a keel or projecting a longitudinal medial line on the lower surface.

carminatives

Herbal medicines that can dispel gas from the intestines, relieving colic.

carnivorous plant

A plant subsisting on nutrients obtained from the breakdown of animal tissue, usually that of insects.

carnose

Fleshy.

Carnoy's fluid

A liquid preservative for cytological materials, containing 3:1 absolute ethyl alcohol and glacial acetic acid.

carotene (alt. carotin)

Orange-yellow hydrocarbon, a pigment which commonly appears in such plants as carrots and squash; a precursor of Vitamin A.

carpel

A simple pistil or one member of a compound pistil.

carpid

Half of a schizocarp, e.g., one of the winged seeds of a maple.

carpogonium

The female organ of red seaweeds.

carpophore

1. The slender prolongation of the floral axis which in the Umbelliferae supports the pendulous ripe carpels. 2. The nonmotile spore of the carposporophyte.

carposporophyte

The post-sexual fruiting stage of a red seaweed.

carr

A fen.

carrying capacity

The maximum number of individuals of a particular species that a given area can maintain indefinitely.

cartilaginous

Hard and tough, but still flexible.

caruncle (syn. strophiole, adj. carunculate)

An excrescence or appendage at or about the hilum of a seed.

caryophyllaceous

1. Refers to members of Caryophyllaceae. 2. Refers to petals which have a long claw at the base.

caryopsis

A grain, such as grasses; a seed-like fruit with a thin pericarp adnate to the contained seed.

cassideous

Shaped like a helmet or hood.

castaneous

Of a chestnut-color; dark brown.

casual

A weed in a cultivated field which appears occasionally but does not naturalize.

casual species

Species which occur rarely in a community, such as a lilac, Syringa, but does not naturalize young plants in the area.

catabolism

Destructive metabolism releasing energy and breaking down complex materials in a living organism.

catadromous

When the first branch of a frond or vein in a pinnate leaf appears on the side facing towards the base.

cataphyll

A leaf, or leaf-like organ, usually found below ground.

catapult fruits

Those fruits that discharge their seeds forcefully; ballistic fruits.

catarobic

Refers to a wet or aquatic habitat where the slow breakdown of organic matter is occurring. Organic materials are given off into the medium with much of the oxygen used, but not enough to prohibit the occurrence of aerobic organisms.

caterpillars

The larvae of butterflies and moths, which often feed on leaves.

cathartics

Potent herbal laxatives.

cation

A positively charged ion.

catkin

A compact and often drooping cluster of reduced, stalkless, and usually unisexual flowers; an ament.

caudate

Having a slender tail-like appendage.

caudex

1. The persistent, sometimes woody base of an otherwise herbaceous stem. 2. A trunk, especially that of a tree fern.

caudicle

The thread-like or strap-shaped stalk of a pollinium.

caulescent

Having a manifest stem above ground.

cauliflory (adj. cauliflorous)

The state of flowering from the branches or trunk.

cauline

Belonging to the stem.

caustic (syn. corrosive)

Capable of destroying by chemical action.

cell

One of the minute vesicles of protoplasm consisting typically of nucleus, cytoplasm, and, in the plant cell, photosynthetic pigments, all enclosed by a cell wall. Any structure containing a cavity, as the cells of an anther or ovary, etc.

cell membrane (syn. plasma membrane, syn. plasmalemma)

A semipermeable limiting layer of cell protoplasm.

cell system pasturing

An attempt to replicate the method of natural grazing by bison. Livestock are placed in one section or cell of pasture with access to water until all vegetation is eaten or trampled to the ground, then moved to the next section. A common pattern features 10 cells with livestock moved monthly so each section is grazed in different months each year to encourage increase of ice cream grasses. See also: continuous grazing, rotation grazing.

cellulose

The complex carbohydrate that is the principal component of cell walls of plants.

cement

A powder of lime and other minerals burned together in a kiln and finely pulverized which, when combined with water, hardens with hydration. It is used as the binding agent in mortar and concrete.

cenospecies

All the ecospecies that may exchange genes through hybridization, like the violets, Viola.

Cenozic

Refers to the geologic era extending from 40 million years ago to the present era, which started approximately a million years ago.

center of dispersal

The geographic area from which a taxon has spread or is spreading, such as where an alien plant was introduced.

center of diversity

A specific locality with high levels of genetic or species variance.

center of endemism

A unique geographic region with species which are known only to that area. See also: endemic.

center of origin

The geographic area in which a taxon originated and from which it is spread.

center pivot irrigation

A method of agricultural irrigation using a long, wheeled arm with many nozzles that pivots about the center of a circle; used primarily in arid regions.

central rays

The short immature ray florets comprising the central portion of the fully double flowers when at their prime stage (used in describing dahlias.)

central strand

The middle of many moss stems is made up of a bundle of much narrower and more slender cells, known as the "central strand".; This is usually continuous with the midrib or costa of the leaves, similar to the vascular bundles in the higher plants.

centrifugal

Progressing or developing outward from the center or axis.

centripetal

Progressing or developing inward from the outside and towards the center or axis.

centromere

The point or region on a chromosome to which the spindle attaches during mitosis and meiosis.

centrum

The central portion; used specifically for the large central air space in hollow stems, such as those of Equistetum.

cephalanthium

The flower head of a Compositae species.

cephalium

A woolly growth at the top of the stem of some cacti, such as Melocactus, on which the flowers appear.

cephalodia

Tiny thalli growing in the upper cortex of some lichens.

cereal

Grain or plants that produce grain--mostly from the Graminae family--used as food.

ceriferous

Wax-producing; waxy.

cernuous

Drooping or nodding capsule, somewhat inclined as opposed to erect.

certified seed

Seeds that have been approved by a legally recognized certifying agency as being qualified under established standards of germination; they are free from disease and weeds and are true to variety.

cespitose (syn. caespitose)

Growing in tufts; forming mats or tufts; often refers to a short plant with many stems or branches, forming a cushion appearance.

chafers

Beetles that attack plant roots as larvae and leaves as adults.

chaffy

Having or resembling chaff.

chain saw

1. A power tool for cutting timber. 2. A tool with interlocking individual teeth that are chained together, with ropes on either end and powered by muscle.

chalaza

The area of an ovule, opposite the micropyle, to which the funicle is attached.

chalk

Soft gray, buff, or white limestone formed from the shells of foraminifers.

channeled

Deeply grooved longitudinally, like a gutter.

chaparral

A dry land, xerophytic, formation of impenetrable thickets, composed of stiff, thorny, small-leaved shrubs.

character

An attribute or property of an organism, functional or structural, which may be adapted through environmental conditions within genetically determined limits.

characteristic diversity

The pattern of distribution and abundance of habitats and their species populations under conditions where human influence on the ecosystem is no greater than that of any other biotic factor.

chart quadrat

A cart or map of a sample area showing the placement and area of each plant.

chartaceous

Having the texture of writing paper or parchment and usually not green.

chasmogamy (adj. chasmogamous)

The opening of the perianth of a flower for the purpose of fertilization. See also: cleistogamy.

chasmophyte

A plant which grows in the crevices of rocks and rock faces. See also: chomophyte.

check dam

A short low dam constructed in a waterway to decrease the sp.ed of stream flow and to allow sediments to drop from the water.

chelate (n. chelator, n. chelation)

The process whereby an organic chemical bonds with and removes free metal ions from solutions.

chemical stratification

A condition found in temperate lakes during the summer and winter stagnation periods in which certain horizontal layers become different chemically from adjacent ones, often causing turnover. See also: thermal stratification.

chemoautotrophic

Being autotrophic and oxidizing an inorganic compound as a source of energy, as a chemoautotrophic bacteria.

chemolithotrophic

Describes an organism which obtains its energy from the oxidation of inorganic compounds.

chemoorganotrophic

Describes a heterotroph which oxidizes chemical bonds for energy but requires organic carbon compounds to grow.

chemosynthesis

A process found in certain bacteria in which nutrition is assured by the ability to oxidize inorganic materials.

chemotaxis

Movement of an organism caused by a chemical stimulus.

chemotrophic

Refers to an organism that produces energy from a chemical reaction which does not depend on light. See also: heterotrophic, autotrophic, phototrophic.

chemotropism

Movement or growth of cells or organisms in response to chemical stimuli.

chemotype

A population of plants belonging to a particular species that differs chemically from others of that species.

chernozem (syn. black earth)

A zonal group of soils with deep fertile surface soil, dark brown to black in color, rich in organic matter, grading into lighter colored soil below, and having a calcium carbonate layer at a depth of 1.5 to 4 feet (45 to 120 cm.). These are often found under tall grasslands in a temperate to cool, somewhat humid climate.

chestnuts soils

A zonal group of soils with dark brown surface horizons grading into lighter colored soil below, and a calcium carbonate layer at depths of one to four feet (30 to 120 cm.). These are associated with grasslands in temperate to cool, subhumid to semiarid climates; moister than brown soils, drier than chernozem.

chianophile

A plant that can endure long snowy winters, or one that requires snow cover in winter.

chianophobe

A plant that does not tolerate long snowy winters, or one that can survive with little or no snow cover during winter.

chiasma

A crosswise fusion, as occurs with chromosomes.

chicon

The blanched, compact shoots of chicory (Cichoricum intybus).

chilling requirements

Seeds which are dormant or doubly dormant may need actual outdoor climatic conditions of winter, or the indoor equivalent known as stratification. This is usually done by placing the seeds in moist soil in a plastic bag in the refrigerator for several weeks or months.

chimara (alt. chimera, alt. chimaera)

A plant formed of the tissues of two different species mingled together and being intermediate in characteristics between the two parents.

chiseling

Working deeply into the subsoil with a chisel plow to break compaction. See also: subsoiling.

chitin

Horny material that forms exoskeletons of insects, arachnids, etc.

chlorenchyma tissue

Parenchyma cell containing chloroplasts found in plants.

chlorinity

The chloride content of a solution, often compared to seawater which is 19.3.

chlorophyll

The green coloring-matter within the cells of plants.

chlorophyllose

Containing chlorophyll.

chloroplast

The microscopic body within the cell which contains chlorophyll.

chlorosis (adj. chlorotic)

A yellowing of the leaves, reflecting a deficiency of chlorophyll and caused by waterlogged soil or a lack of nutrients, often iron.

chlorotic

Refers to a plant that has chlorosis.

cholagogues

Herbal medicines which promote the flow of bile from the liver.

chomophyte

A plant that grows on rock fissures or crevices, on rocky ledges. See also: chasmophyte.

choripetalous

Refers to a corolla made up of separate petals. See also: polypetalous.

chorology

The study of regions or areas. See also: synchorology.

chresard

Water in soil that is available to plants for absorption.

chromatid

One of the usually paired and parallel strands of a duplicated chromosome joined by a single centromere.

chromatin

Material of the nucleus and chromosomes which can be stained deeply with certain dyes.

chromatophore

1. In plants, a plastid which contains pigment in a cell such as a chromoplast or chloroplast. 2. In animals, a cell or group of cells with pigment having the capability of color change.

chromogen (adj. chromogenic)

A pigment-producing microorganism.

chromoplast

A plastid other than a chloroplast, containing yellowish or red pigment.

chromosome

One of the set of bodies in the nucleus which determines the hereditary cell structure and function of a cell.

chrysalis

A pupa of a butterfly; broadly, any insect pupa.

Chrysophyta

A taxonomic division containing diatoms, golden-brown algae, and yellow-green algae, all single-celled and normally found in marine environments.

chubasco

A spinning disturbance near the Gulf of California, resembling dust whirls on land and waterspouts over water. These environmental disturbances reach great heights, becoming violent enough to capsize small craft.

chylocaulous

Refers to fleshy stems, like cactus.

chylophyllous

Refers to fleshy leaves, like agave.

ciliate

Marginally fringed with hairs (cilia).

cilium (pl. cilia)

A short, usually stiff, usually unicellular, marginal hair; a hair-like thread of the endostome, alternating with the segments.

cincinnal

Refers to scorpoid cymes and other curled floral arrangements.

cincinnus

A monochasial cyme on which flowers appear in an order along a spiral.

cinereous

Ash-colored.

cinnamomeous

Cinnamon-colored.

circinate (alt. circinnate)

1. Curved into a circle so that the apex is nearly or quite bent around to the leaf base. 2. Coiled in a spiral, with the apex at the center. 3. Coiled from the top downward, as the young frond of a fern.

circle of vegetation

All of the species and communities that are restricted to a natural vegetation unit.

circulus

One of the concentric circles on a fish scale.

circumboreal

Said of plants which surround the Northern Hemispere, appearing in both the Old and New Worlds, such as the dandelion.

circumpolar

Refers to species that occur all around the poles in either the north or south and in both the eastern and western hemispheres.

circumposition

A propagative method also known as air layering.

cirque

A deeply-eroded area with steep slopes in a region of past glaciers.

cirrate (syn. cirrhate)

Applied to leaves which curl up in drying. Cirrate leaves are more regularly curled than crispate leaves.

cirrhose

Having a wavy hair point.

cistern

An artificial reservoir for collecting and storing rainwater, as the type used for irrigation, which is often ornamental in design and frequently serves only as a decorative function.

citation

In botanical systematics, a quotation from a book or author referencing an authority or precedent.

CITES (alt. C.I.T.E.S.)

The Convention on International Trade of Endangered species, which provides regulations for the international trade in listed species of plants and animals.

citronella

A fragrant oil used in perfumery and as an insect repellent derived from the grass Cymbopogon nardus.

citrus

Members of the family Rutaceae, e.g., oranges and limes, etc., grown in warm areas as edible fruits.

cladocarporus

Having the sporophyte terminating a short special fertile branch; somewhat like half-way between acrocarpous and pleurocarpous.

cladophyll (alt. cladode)

A flattened, leaf-like photosynthetic stem or branch not itself leaf-bearing.

clambering

Describes a plant that sprawls or climbs but lacks tendrils.

clasping

A leaf whose base wholly or partly surrounds the stem.

classification

Systematic arrangement of hierarchal levels of taxonomy.

clathrate

Lattice-like; having thick lateral (adjacent) cell walls and thin surficial walls.

clavate

Club-shaped; gradually thickening from a slender base.

clay soil (syn. clay loam)

A soil, usually heavy and poorly drained, containing a preponderance of very fine particles.

clean cultivation

Hoeing out weeds and keeping the surface of the soil loose to lessen weed seed germination.

clearcut (alt. clear felling)

The cutting of all trees in a forest.

cleft

Divided nearly to the midvein.

cleistocarpous

Capsule opening irregularly, not by a lid or valves.

cleistogamy (adj. cleistogamous)

The condition of having flowers which self-pollinate in the bud, without the opening of the flower. See also: chasmogamy.

climax stage (alt. climax community)

The ultimate stage in the process of succession, occurring when a plant's ecosystem has reached a point of stability.

climber

A plant that can climb given support.

clinandrium

In Orchidaceae, the part of the central column which holds the anthers.

cline (adj. clinal)

A gradual morphological or physiological change in a group of related organisms across their range, usually correlated to environmental or geographic transition.

clinker

The material that emerges from the cement kiln after burning. It is in the form of dark, porous nodules which are ground with a small amount of gypsum to produce cement.

cloche

Covers for individual plants, protecting against frost, birds and pests; a miniature cold frame.

clod

A lump of soil.

clone

A group of plants all originating by vegetative propagation from a single plant, and therefore genetically identical to it and to one another.

cloud forest

A mountain forest covered by a persistent mist that creates stunted trees and abundant epiphytes.

club root

A fungus that causes knobby roots in stocks, wallflowers, and other members of the cabbage family.

clump-forming

Describes a plant which reproduces vegetatively, forming smaller crowns around the parent which can be divided and planted in new locations.

cluster

A group of two or more occurring close together.

clypeate

Halberd or shield-shaped.

co-management

The sharing of authority, responsibility, and benefits among government, businesses, and local communities in the management of natural resources, e.g., cooperation among the National wildflower Research Center, Texas Department of Agriculture, landscape architects, and nurseries in the production of native plants for landscaping.

coalesce

To fuse together.

coalescence

The union of parts or organs of the same kind.

coarse-toothed

With large teeth; dentate, serrate.

cob

The rachis of the female corn spike, fruit of Zea mays.

cobblestone

A naturally rounded stone larger than a pebble and smaller than a boulder; especially such a stone used in paving a street or in construction.

coccus (pl. cocci)

A lobe of a schizocarp containing a single seed.

cochlear

Describes a coiled arrangement of the corolla lobes in a bud, a type of imbricate aestivation.

cochleariform

Rounded and concave like a spoon or ladle.

cochleate

Spiral, like a snail's shell.

cocous (pl. Cocci)

One of the parts into which a lobed fruit with 1-seeded cells splits.

Codes of Nomenclature

The general rules for the assignment of scientific names to taxa.

codominant leaders

When two main branches of a tree are of equal strength and size, leading to the possible danger of the tree splitting.

coefficient of association

A mathematical statement of the frequency of occurrence together of two species not due merely to chance, calculated by dividing the number of samples in which both occur by the number of samples in which it would be expected they both would occur.

coensorus

In ferns, the extension of a sorus, or united sori that appear to be a single sorus.

coetaneous

Of the same age or existing at the same time.

coexist (n. coexistence)

To live together in the same place and at the same time.

coherent

Refers to parts that are usually separate but have become fused together, such as petals in a floral tube.

cohesion

The union of one organ with another of like nature.

coir

A stiff coarse fiber from the outer husk of a coconut.

cold frame

A frame covered in glass or plastic and without artificial heat used to protect plants and seedlings outdoors.

cold room

An area to keep plant specimens fresh until they can be pressed.

coleoptile (alt. coleophyll)

The first leaf following the cotyledon of a monocotyledon which forms a protective sheath around the plumule.

coleorhiza

Protective sheath around the radicle in a grass embryo.

collateral

Situated side by side.

collecting permits

Papers granting permission to collect specimens of flora of parks, nature preserves, foreign countries, or other protected areas.

collection bottles

Glass or plastic bottles with waterproof screw tops or vial type bottles, used to collect specimens such as pollen, buds, bark, seeds, insects, etc.

collenchyma

A type of supportive tissue consisting of elongated cells with thickened walls and containing chloroplasts.

colleter

A group or tuft of mucilaginous secretory hairs, often found near the base of the leaf lamina and on the calyx in memebers of the Apocynaceae and Asclepiadaceae families.

colliculate

Having small hill-like eminences.

colloidal clay

Extremely fine, microscopic particles of rock.

colloidal dispersion

A mixture containing particles larger than those found in a solution but small enough to remain suspended for a very long time. See also: colloidal suspension.

colloidal suspension

Minute particles remaining intermixed in a liquid without being dissolved. See also: Brownian movement, colloidal dispersion.

collum

The neck or tapering base of the capsule.

colonial

Forming colonies by means of underground rhizomes, stolons, etc.

colony

A group of lichen thalli growing together.

color charts

Hue chips used to simulate colors in the field, as flowers may lose or change color(s) when dried. Examples of such charts are the horticulture Society Color Chart, Nickerson Color Fan, and Horticultural Color Chart.

colporate

Describes a pollen grain which has both an elongated and a rounded aperture.

colpus (pl. colpi, adj. colpate)

An elongated aperture of a pollen grain with a length/breadth ratio greater than 2. See also: colporate, porate.

columella

In mosses, the central axis of the capsule; around it and between it and the outer wall of the capsule are borne the spores. Sometimes the lid adheres to it and is raised upon it.

column

In orchids, a structure formed by the union of stamens, style, and stigma.

column foot

In Orchidaceae, the basal platform to which the lip is attached to the column.

coma

Comal tuft, a tuft of leaves at the tip of a stem or branch.

combination

In taxonomy, the name below the rank of genus, which combines the genus name along with the species and lower ranks, such as subspecies, variety, etc.

commensalism

A type of symbiosis where there are two organisms from different species. One obtains food or other benefits from the other without damaging or benefiting it.

commercial synonym

1. An alternative choice of a legitimate name for a cultivar. 2. A shortened form of the original name, used where the original name is not conducive to sales, e.g., Ilex vomitoria. 3. A sales name chosen by the originator of the cultivar or with the originator's approval.

commissure

The surface by which one carpel joins another, as in the Umbelliferae.

common name

Identifying term which often reflects appearance, legend, or use of a plant species. It may var. greatly by region, increasing the need for standard binomial nomenclature.

common property resource management

The supervision of a specific resource (such as a forest or pasture) by a well-defined group of users with the authority to regulate its use by members and outsiders.

comose

Furnished with or resembling a tuft of hairs.

compact

Pressed together or closely joined; in rhizomes, those with short internodes and closely spaced stipes.

companion plants

1. Plants which work well together aesthetically, perhaps because they have complementary coloring, or flower at different times of the year, etc. 2. Two or more plants that are used together because one or more are beneficial to one or more of the others, for instance by repelling pests that prey on the other(s).

comparative advantage

Relative supremacy with which a region or state may produce a good or service.

complete fertilizer

A compound containing the three essential minerals for growth: nitrogen (N), phosphorous (P), potassium (K).

complete flower

Having all the principal parts, particularly the stamens and pistils.

complex

A group of very similar and obviously related plants where it is difficult to find identification limitations, and where the relationships are not fully understood.

complicate

Folded upon itself; folded lengthwise.

composite

Member of the family Compositae, having compound flower heads, e.g., the daisy, the aster, the sunflower, etc. See also: compound flower head.

composite cultivar

A group composed of several closely related cultivars; grex.

compost

Decomposed organic maker, usually used to enrich the soil.

compound

Composed of two or more similar parts united into one whole. Compound leaf: one divided into separate leaflets.

compound flower head (alt. composite flower head)

A flower head with outer ray flowers forming petals surrounding the inner disc flowers, as in the Compositae.

compound leaf

A leaf divided into smaller leaflets.

compressed

Flattened, especially laterally.

concatenate

Linked, as on a chain.

concave

Depressed or hollowed out.

concavo-convex

Bulging out on one side and caving in on the other, like an eggshell or lens.

concentric

Having a common center, as the rings on a target.

conceptacle

A flask-like structure containing reproductive organs.

conceptual design

Rough drawing showing the general shape and location of all design elements such as buildings, fences, slopes, plantings, etc. in a landscape plan.

concolorous

Uniform in color.

concressant

Growing together, especially of parts that were originally separate.

concrete

A hard compact building material formed when a mixture of cement, water, sand, gravel, and perhaps other aggregates, undergoes hydration.

concretion

Mineral mass formed within another type of rock, often very different in appearance and composition.

conduplicate

Folded together lengthwise.

cone

A conical fruit consisting of seed-bearing, overlapping scales surrounding a central axis.

cone-scale

One of the scales of a cone.

conferted

Closely crowded. See also: congested, constipate.

confervoid

Formed of fine threads, as green algae.

conflorescence

A compound inflorescence consisting of two or more simple inflorescences.

confluent

Running into each other; blended into one.

conform

Similar in shape and size to others.

confused center

A flower center whose petals are disorganized, not forming a pattern.

congeneric

Belonging to the same genus.

congested

Close together. See also: conferted, constipate.

congregate

Growing in dense proximity.

conical

Cone-shaped; widest at the base and tapering to the apex.

conical root

A taproot.

conifer

A cone-bearing tree of the pine family, usually evergreen.

coniferous

Cone-bearing.

conjugation

The union of gametes.

connate

United; used especially of like structures joined from the start.

connate-perfoliate

Where opposite leaves are completely joined at the bases, leaving the appearance that the stem pierces through.

connective

The portion of a stamen which connects the two cells of the anther.

connivent

Coming into contact; converging, but not fused.

conoidal

Nearly conical.

conservation lists

Recommended protection lists of endangered, threatened, and protected plants, giving information from groups other than those with enforcement powers.

conservatory

A structure or room made primarily of glass and used for the cultivation of tender and exotic plants. A formal term for a greenhouse.

conspecific

Belonging to the same genus.

conspicuous

Easily visible without a lens, often extended to mean showy or prominent.

constricted

Used of capsules that become narrowed under the opening when dry.

construction documents

Final drawings with accompanying written specifications to be used by contractors in completing a landscape project.

consumers

Organisms which break down organic material (such as sugars and proteins) to obtain energy for their own growth, and then return inorganic components to the environment, where they are again available.

container gardening

Cultivation of flowers and vegetables in boxes, urns, garbage bags, etc., where direct soil planting is not feasible, as on apartment balconies, in penthouses and desert areas, etc.

container-grown

Grown from a seedling in the container it is to be sold in.

contiguous

In immediate contact.

continental

Describes a climate little influenced by sea, with large ranges between summer and winter temperatures.

continuous

Not interrupted.

contorted

Irregularly twisted or distorted.

contracted

Reduced in size by or as if by squeezing or forcing together.

contractile roots

Roots that can shorten themselves much like a worm does, drawing the plant down deeper into the soil. They usually have a wrinkled surface for expanding and contracting.

controlled burn

A fire started to rid an area of flammable materials in order to prevent a more dangerous or costly wildfire.

convariety (alt. convar)

A group of similar cultivars within a variable species or hybrids between two species; the term has now been replaced in most cases by the word "group".

convergent

Coming in contact, but not fused.

convex

Arched outward.

convolute

Rolled up longitudinally.

coppice

1. A thicket or copse of small trees. 2. To cut a plant almost to the ground each year so as to produce more vigorous growth.

copse

A thicket of small trees or shrubs.

coralloid

Shaped like coral, with many branches.

cordate (alt. chordate)

Heart-shaped with the point away from the stem.

cordiform

Heart-shaped in all three dimensions.

cordon

A woody plant, most often a fruit tree, trained to grow as a single stem on a support.

coriaceous

Leathery in texture.

corm

The enlarged fleshy base of a stem, bulb-like but solid.

cormel (alt. cormlet)

A small corm that develops at the base of the mother corm.

cormophyte

A land plant belonging to the former botanical division Cormophyta, having a stem and root system.

cormous

Bearing corms.

corn fork

A fork shaped like a scoop shovel, but with tines instead of a blade.

corneous

Having a horny texture.

cornicle

Wax-secreting tubes of certain insects, such as aphids.

corniculate

Having horn-like projections.

cornucopia

Curved horn overflowing with edible produce, symbolizing abundance.

cornucopiate

Shaped like a cornucopia or horn.

cornute

Spurred or horned.

corolla

The petals of a flower; the inner perianth of distinct or connate petals.

corolline corona

Fleshy ridges or outgrowths of tissue attached to the corolla tube.

corona

A crown of appendages between the corolla and stamens, or on the corolla or stamens. See also: crown.

coroniform

Shaped like a crown.

corpusculum

The central part of a pollinarium, characteristic of the families Orchidaceae and Asclepiadaceae.

corrugate

Wrinkled or in folds.

cortex

1. In rhizomes and other axes, the tissue between the stele and the epidermis. 2. In lichens, the outermost layer of the thallus. 3. In seaweeds and fungi, the tissue external to the central tissue of longitudinal cells.

corticate

Having a cortex.

corticolous

Growing on the woody parts of trees and shrubs.

corymb

A flat-topped or convex open flower cluster, the outer flowers opening first. In the stricter use of the word, equivalent to a contracted raceme and progressing in its flowering from the margin inward.

corymbose

In corymbs, or corymb-like.

cosmopolitan

Widely distributed over the world.

costa

A rib; a midrib or mid-nerve of a pinna or moss leaf.

costapalmate

Ribbed or veined palmately.

costate

Having a costa. Ribbed; having one or more longitudinal ribs or nerves.

costule

An axis that is a branch of a costa or another costule.

cottage garden

A usually small, informal garden making optimal use of space.

cotyledon (syn. seed leaf)

One of the first leaves to appear after germination (there may be one, two, or more); the foliar portion of the embryo as found in the seed. See also: true leaf.

cotype

An additional type herbarium specimen from which the taxon is described.

counteradaptation

Reciprocal acclimation of two or more species to each other over a period of time.

counterirritant

Herbal preparations that produce irritation when applied locally to stimulate circulation in the area of another irritated area.

cove

A small bay, especially on inland lakes.

crateriform

In the shape of a saucer or shallow cup; hemispherical or more shallow.

creeper

A plant running along at or near the surface of the ground and rooting. See also: creeping.

cremocarp

A dry fruit consisting of two one-seeded carpels that separate into mericarps upon ripening; schizocarp.

crenate

Dentate with the teeth much rounded.

crenulate

Finely crenate.

crescentic

Shaped like a crescent moon.

crest

A fan-like appendage, as can be found on some fern fronds; in spores, a tall, irregular ridge.

cretaceous

Chalky.

cribose

Peristome teeth perforated with small apertures.

crinite

Bearded with long weak hairs.

crinoid

Like a lily.

crispate (syn. crisped)

Frizzled, curled, and twisted in various ways.

crisped

Curly-edged, as seen on some fern fronds.

crispy-hairy

With ringlets.

cristate

Bearing an elevated appendage resembling a crest.

crop rotation

Process whereby a different crop is planted in a field each successive year, preferably the following crop utilizing nutrients not greatly used by the preceding crop. Insect and disease vectors are also controlled by rotation.

crosier (alt. crozier)

The unopened coiled leaves of some ferns, especially on the dormant crown.

cross-fertilization

Fertilization by the joining of gametes from different individuals of the same species (cross-pollination), or from different species (hybridization).

cross-pollination

The transfer of pollen from the anther of the flower of one plant to the flowers of a different plant.

crotch

The angle formed between two joining branches.

crown

1. The site on a plant where roots join the stem. 2. In trees, the branches, twigs, and leaves that form the top of a tree. 3. The corona. 4. In roses, the region of the bud union; the point near soil level where the top variety and the understock are joined. 5. An inner appendage to a petal or to the throat of a corolla.

crown gall

Galls on shoots or roots of shrubs, especially those of the rose family, caused by soil bacteria.

crownshaft

An apparent extension of the bole in some Palmae, formed by overlapping and sheathing bases of the leaves.

cruciate

Cross-shaped.

crucifer (adj. cruciferous)

Any plant of the family Cruciferae, including the cabbage, radish, turnip, and mustard.

crumpled

Corrugate; wrinkled.

crushed granite

Pea-sized chips of granite used for paving.

crustaceous

Of hard and brittle texture.

crustose

A form of lichen lacking a lower cortex and rhizines and having thalli that grow in contact with the substratum.

cryogenics

1. The branch of physics dealing with the effects and production of very low temperatures, as applied to living organisms. 2. Dormant preservation by freezing, drying, or both.

cryptogam

A general name for plants, and plant-like organisms that lack flowers and are not reproduced by seeds, e.g., including ferns, mosses, fungi, and algae. The name is close in translation to something like "hidden marriage."

cryptopore

A stoma which is immersed.

crystalline

Looking like crystals or having the nature of crystals.

cube (adj. cubical)

A solid with six equal square sides.

cubiform

Shaped like dice.

cucullate

Hooded or hood-shaped; cowled.

cucullate calyptra

In mosses, a calyptra that is hood-shaped and split on one side only.

cucullus

A hood-like tissue on some seeds.

cucumiform

Shaped like a cucumber.

cucurbit

Any of the various twining or climbing plants of the family Cucurbitaceae, including the melon, gourd, squash, etc.

culm

The peculiar aerial stem which bears flowers, found in grasses, sedges, and rushes.

cultigen

A plant developed in horticulture and found only under cultivation or as an escape.

cultispec

A cultigen that should be given species recognition.

cultivar

An unvarying variety of plant produced by selective hybridization, or, sometimes found in wild populations, and maintained by vegetative propagation or by inbred seed.

cultivar class

A taxon consisting of a group of cultivars.

cultivate

To work the soil in order to break it up and remove weeds.

cultivation

1. A term for the tilling of soil. 2. Working up the bare soil around plants to kill weeds and allow air and water to penetrate to plant roots.

cultivator

A tool which may range in size from a hand-pushed garden implement to sets of teeth attached to a tractor, for the purpose of digging weeds and rounding soil over the base of plants.

culton

A recognizable plant originating in or maintained by cultivation, reflecting that not all such entities must remain cultivars.

cultriform

Curved like a short, wide scimitar.

cuneate

Wedge-shaped; triangular with the acute angle downward.

cup

The cup-like involucre surrounding an acorn. See also: crateriform.

cupped form

Having an open center, with the stamens visible.

cupreous

With coppery appearance.

cupressoid

With foliage like cypress; Cupressus.

cupule

A cup-shaped anatomical structure, like that holding an acorn, which is made of hardened, joined bracts. See also: crateriform.

cupuliform

Cup-shaped.

cure

The hardening of concrete, often controlled by keeping it moist.

curvate

Flexing or bending from a straight line.

curvinerved

Having curved parallel veins, as the leaf of a dogwood.

cusp

A short, abrupt, rigid point. See also: cuspidate.

cuspidate

Tipped with a cusp or sharp and rigid point. See also: cusp.

cut flower garden

An area set aside for the growing of plants which are to be used for the production of flowers for arrangement inside the house.

cut flowers (alt. cutting flowers)

Species of flowers which are removed from the plant for arrangements and which easily retain their freshness.

cuticle

Skin or epidermis. The waterproof layer of the epidermis of plants.

cutin

A thin waxy covering on the outer layer of a leaf.

cutting

What growers of houseplants call slips, used for propagating new plants. The method involves cutting or breaking off a part of the plant, inserting it in growing medium so it can grow a new plant like the one from which it came. Hardwood cuttings are mature wood; softwood cuttings are taken in spring or early summer from tips when plants are actively growing; semihardwood cuttings are taken in late summer or fall when growth has slowed and wood is beginning to harden.

cutting garden

A garden of flowers which can be cut and used in arrangements.

cutwater

A V-shaped projection at the base of a pier or bridge support used to deflect the force of water in a river or stream.

cutworms

Soil-living brownish caterpillars that feed at night, often severing stems of herbaceous plants.

Cyanophyta

A taxonomic division containing cyanophytes, cyanobacteria, and blue-green algae. These may be single cells or colonies, and reproduce by fission. They are found in many environments: damp soil and rocks, fresh water, and salt water.

cyathiform

Cup-shaped.

cyathium (pl. cyathia, adj. cyathiform, adj. cyathophorous)

Cup-shaped. An inflorescence with unisexual flowers surrounded by a cup-like cluster of involucral bracts, e.g., a poinsettia.

cycad

Any plant of the order Cycadales, consisting of palm-like, cone-bearing, evergreen tropical plants that reproduce by means of spermatozoids and have large pinnately compound, usually fan-shaped leaves.

cyclone (adj. cyclonic)

1. A hurricane or typhoon; winds blowing counterclockwise in the northern hemisphere and clockwise in the southern hemisphere, at sp.s of 90 to 130 miles per hour (150 to 217 km/hr) around a calm center, with a forward thrust of 20-30 mph (33-50 km/hr) and a width of 50 to 900 miles (83-1500 km) diameter. 2. Popularly, any storm moving in a circular motion like a tornado.

cygneous

Curved suddenly downward, like a swan's neck.

cylindraceous (alt. cylindric, alt. cylindroid)

Rod-shaped.

cylindrical

Having the shape of a cylinder.

cymbiform

Boat-shaped.

cyme

A usually broad and flattish determinate inflorescence, i.e., with its central or terminal flowers blooming earliest.

cymose

Bearing cymes, or cyme-like.

cymule

A small cyme, usually sparsely flowered.

cystocarp

A carposporophyte contained in a wall of sterile filaments.

cystolith

A concretion within a cell cavity consisting of calcium carbonate and occurring in plants such as figs.

cytokinin

Any of various plant growth hormones, such as kinetin, that grow and promote cell division and delay the senescence of leaves.

cytology (adj. cytological)

The study of cells.

cytoplasm

The part of the protoplasm that is not the nucleus.

cytoskeleton

The network of protein filaments and microtubules in the cytoplasm that controls cell shape, maintains intracellular organization and, in some organisms, is involved in cell movement.

D horizon

The soil layer below the effect of weathering, made up of undifferentiated and unconsolidated parent materials, located immediately below the c horizon. See also: A horizon, B horizon.

dactyloid (alt. dactylose)

Finger-like.

dale

A vale or valley.

damping off (alt. dampen off)

Collapse of small seedlings due to fungi attacking stem at soil level.

dark reaction

Those chemical reactions in photosynthesis not requiring the presence of light and involving the reduction of carbon dioxide to form sugar. See also: Calvin cycle.

data retrieval

The process--manual or automated--of identifying and locating specific facts in stored documents, published or unpublished, and specimen collections of interest to particular uses. See also: literature retrieval, document retrieval.

day degrees

The mathematical statement of the sum of degrees above a threshold for a designated period, such as those above freezing for the growing season. See also: temperature summation.

day-neutral plant

A plant that blooms when the length of day is either long or short. See also: photoperiodism.

dbh

An abbreviation for the phrase "diameter at breast height", a measurement of the thickness of a tree trunk about four feet from the ground.

deadhead

To remove the blooms after flowering to encourage the development of new flowers.

dealkalization

Removal of base ions from soil by leaching or by chemical treatment with exchangeable sodium. See also: alkali soil.

decaploid

Having ten sets of chromosomes.

decapod

Animals like lobsters and crabs from the order Decapoda, class Crustacea.

decidulignosa

Communities of deciduous trees and shrubs.

deciduous

1. Not persistent. 2. A tree losing its leaves at the end of the growing season; nonevergreen.

declinate

Bending downwards.

decomposer

Any of various organisms, usually a bacterium or fungus, that breaks down organic substances making the nutrients available again.

decomposition

The breakdown of tissues and compounds into simpler substances which act as soil nutrients.

decompound

More than once compound or divided.

decordicate

Lacking a cortex.

decreaser

A species that gradually disappears under continued grazing. See also: increaser, population density, cover.

decrescent

Becoming gradually less.

decumbent

Reclining, but with the tip ascending.

decurrent

Describes a leaf that extends down the stem below the insertion.

decurved

With a downward curve.

decussate

Alternating in pairs at right angles.

deep watering

Inundating an area with water for a long period of time, perhaps 24 hours or more, to permeate the deepest layers of subsoil, thereby pulling roots down where they will not easily perish from drought.

deferred grazing

The delay of grazing in forage after growth has started, until development has reached a stage that will promote additional vigor of the plants. See also: cell system pasturing, continuous grazing, rotation grazing.

deficiency disease

A stress condition or disease of an organism caused by lack of a nutritive substance such as a vitamin or mineral.

definite

Of a constant number, not exceeding 20.

deflected

Bent downward at a sharp angle.

deflexed

Bent or turned abruptly downward.

deflocculation

Soil aggregates containing clay separating into individual particles.

deflorate

Flowering has completed for the season.

defoliant

A chemical substance which causes a plant to drop its leaves.

defoliate (n. defoliation)

1. To cause the leaves of a plant to drop. 2. To remove the leaves of a plant.

deforestation

Clearing trees from a woodland, often done to promote food for wildlife as well as to provide timber.

deformed

Misshapend, distorted.

degradation

Loss of friability or fertility of soil resulting from leaching.

dehisce

To split apart and discharge seeds or spores.

dehiscence (adj. dehiscent)

1. Breaking open at maturity to discharge seeds or spores. 2. Opening regularly to let seeds or spores escape by valves, slits, etc., as a capsule or anther. See also: indehiscent.

dehorning

Severely pruning shrubs or trees, often carried to extremes of butchery.

delicate

Fragile; easily broken.

deliquesce (n. deliquescence, adj. deliquescent)

1. To branch into many subdivisions and lacking a main axis. 2. To liquefy or become soft with age, as occurs with some fungi.

deltate

Broadly triangular with an obtuse apex.

deltoid (alt. deltate)

A low triangle attached at the middle of the wide part, rather than at the point; shaped like the Greek letter delta.

demarcation

An outline, boundary, delimitation, separation.

deme

One or more populations of a taxon; a population that will interbreed.

demersed

Constantly under water.

demography

The study of populations and their analysis regarding reproduction, deaths, age, etc.

demulcents

Herbal medicines that can break up phlegm or other mucus; sometimes used externally to sooth and soften skin.

dendroid (alt. dendritic)

1. Shaped like a tree. 2. Arranged in a shape like a tree, like some hairs on Cruciferae.

dendrology

The study of woody plants.

denitrification

The loss or removal of nitrogen or nitrogen compounds; specifically, a reduction of nitrates or nitrites caused by bacteria that usually results in the escape of nitrogen into the air.

density-dependent factor

An influence that hinges on a certain density of individuals to be fully effective, like peach trees or Amygdalis that must be 75 feet or closer for insects to successfully cross pollinate them.

density-independent factor

An influence that is effective regardless of density of a population, like the influence of a drought. Some scientists dispute the existence of such a factor. See also: nonreactive factor.

dentate

Toothed, usually with the teeth directed outward.

dentation

The teeth along the margin of an organ.

denticle

A small tooth; in plants of the family Rubiaceae, thick papillate tubercles along the margin of the interpetiolar stipules.

denticulate

Minutely dentate.

dentiform

Tooth-shaped.

deoperculate

Applies to a capsule after its lid has detached.

deoxyribonucleic acid (abr. DNA)

The chief material constituting genes and chromosomes.

depauperate

Starved; prevented from coming to its natural size through lack of nourishment.

dependence

An association between organisms in which the dependent one receives benefits but gives no benefit to the other, characteristic of such plants as mistletoe, Phoradendron, living on an oak, Quercus; not reciprocal. See also: symbiosis, competition, coaction, parasite.

dependency zone (alt. dependency range)

A belt surrounding an area of private land which supplements the use of the private land with additional use of public land.

dependent property (alt. dependent range)

Privately controlled land or water assumed to have special claim for use of public or cooperatively controlled range.

deplanate

Flat.

depressed

Somewhat flattened from above.

desalinization

1. The process of removal of salt from sea water to make drinking water. 2. Removal of salts from soil, usually by leaching.

descending

Bending gradually downward.

description

A list of characters which gives the attributes or features of a specific taxon.

desert grassland

Areas of the southwestern united States characterized by several species of adapted deep-rooted grasses such as grama grass, three awn grass, and curly mesquite.

desert pavement

The stony surface of dryland areas when fine materials have disappeared from actions of water and wind.

deserta

Various types of plants found in areas that are low in available water like arid deserts, saline deserts, permafrost deserts, tundra, strand vegetation, and rocky mountainsides.

desiccate (n. dessication)

To dry up.

desilting area (alt. desilting basin, settling basin)

An expanse set aside above a dam, pond or field solely for the deposit of silt and debris from flowing water. See also: detention basin.

detention basin (alt. detention dam, detention area, detention pond)

A man-made holding area for the purpose of storing sewer overflow and surface runoff until such time as the water may be released for treatment without causing flooding.

determinate

Having growth where a bud or flower terminates the growing tip, e.g., a determinate inflorescence.

dethatcher (alt. de-thatcher)

A tool which combs clippings and thatch to the surface of the lawn.

detritivores

Organisms such as fungi, bacteria, and earthworms which consume nonliving material.

detritus

1. Any loose material that has separated from a mass, such as gravel from a rock face.

Devonian

A geological period in the Paleozoic era, which lasted from about 325 million years to 45 million years ago.

dew point

The temperature at which air is capable of holding no additional water vapor, with either a drop in temperature or an increase in water vapor causing the vapor to condense into liquid as rain, fog, or dew. During the course of precipitation, the relative humidity is 100 percent and the saturation deficit is zero.

dextrorse

Turned to the right.

diagonal

The average, a compromise of position.

dialypetalous

With separate petals.

dialysis

Separation of dissolved substances by their unequal diffusion through semipermeable membranes.

diameter at breast height (alt,. diameter breast high, abr. d.b.h., abr. DBH)

The width of the trunk of a standing tree, measured at 4.5 feet (1.3 meters) above ground surface.

diandrous

With two perfect stamens.

diaphanous

Very thin and transparent or translucent.

diaphoretics

Herbal medicines that promote perspiration and lower temperature.

diaphragm

Dividing membrane or partition.

diaspore

A reproductive portion of a plant like a seed or bud, that is dispersed and may give rise to a new plant. See also: disseminule.

diastrophism

Displacement of the earth�s crust by folding or slippage, causing the formation of mountains, chasms, etc.

diatom

Any of the minute planktonic unicellular or colonial algae of the class Bacillariophyceae, which contain silica.

diatomaceous ooze

Material consisting of siliceous remains of diatoms, found in cold seas.

dibble (alt. dibber)

A small hand implement used to make holes in the ground for plants, seeds and, most often, bulbs.

dibrachiate

Refers to branches that spread widely.

dicarpellary

Composed of two carpels.

dichasium

A cyme with opposite branching below the terminating flower.

dichlamydeous

Describes a flower which has two whorls of perianth parts.

dichloro-diphenyl-trichlorethane (abr. DDT)

An insecticide extensively used during the period after World War II that is now outlawed in the united States and most of the industrialized world.

dichogamy

The differing times of maturation of stamens and pistils in a flower.

dichotomous

Forking regularly by pairs.

dichotomous key (syn. floral key)

A series of choices leading to the identification of a species.

dichotomy

The division of a growing point into two halves.

diclinous (alt. diclinic)

Having the stamens and the pistils in separate flowers.

dicotyledon (adj. dicotyledonous)

A flowering plant with two cotyledons.

dicoumarol

A compound derived from spoiled sweet clover hay and used to delay clotting of blood.

didymous

Twin; found in pairs.

didynamous

Refers to stamens found in two pairs of unequal length.

dieback

The dying of the outer portions of a plant due to disease or weather damage; death of part or all of the woody portion of a plant.

diel

The 24-hour period of night and day. See also: diurnal, nocturnal, crepuscular.

differential species (alt. differentiating species)

A species with high fidelity to a particular community that can be used to distinguish vegetation units.

differentiation

1. Maturation of a cell, organ, or immature organism from juvenile to adult status. 2. The development of new kinds of organisms in the course of evolution.

difform

Not similar.

dig in

To bury during the process of turning soil for planting, as occurs with compost, fertilizer, etc.

digamous

With both sexes in the same flower cluster.

digestion

The conversion of complex organic substances into simpler fats, proteins, and carbohydrates by chemical reactions and enzymatic processes.

digitalin

One of the mixtures of glycosides used in making digitalis.

digitalis

A drug derived from the seed and dried powdered leaves of plants of the genus Digitalis containing important glycosides and serving as a powerful cardiac stimulant and a diuretic.

digitate

Finger-like; compound, with the members arising together at the apex of the support.

digonous

Two-angled, as are the stems of some cacti.

digynous

With two separated carpels or styles.

dihybrid

A crossbreed; an organism that came about from the breeding of parents that differ in at least two characters, e.g., leaf shape and plant height.

dike

An embankment built to protect land from flooding or erosion, or to stop the loss of water from wetlands.

dilettante

A rather derogatory term for one who becomes interested in one field, then another, never delving deeply into any of them, an amateur, or at best a generalist.

dimerous

Having all the parts of the flower in twos.

dimidiate

Halved diagonally, or as if one half was wanting.

dimorphic

Having two shapes; in ferns usually refers to fertile versus sterile laminae or portions of laminae.

dimorphism

The state of a plant or animal showing two forms or colors in the same population, e.g., snowshoe rabbits with winter white and summer brown coats. See also: polymorphism.

dimorphous

Occurring in two forms.

dioecious (alt. diecious)

Unisexual, with male and female flowers on separate plants.

dip

A depression, as between two sand ridges.

diplecolobous

Describes cotyledons in a seed which are twice folded transversely.

diplochory

Describes seed dispersal involving two or more modes. For instance, a bird eats a fruit and disperses seed in it's droppings and these are later carried away by insects.

diploid

Having two sets of chromosomes.

diplostemonous

The stamens of the flower are arranged in two separate whorls, the outer one with stamens alternate with the petals, the inner one opposite the petals.

direct seeding

Planting straight into soil where the plant is to grow rather than germinating seeds indoors and transplanting.

direct sunlight

Unobstructed sunlight. See also: skylight.

dirt

Soil.

disarticulating

Breaking apart at the joints when mature.

disbudding

The removal of the side flower buds around a central bud to induce extra-large blooms; or to selectively remove buds to conserve strength in a newly-transplanted perennial.

disc floret

One of the small tubular, actinomorphic florets which make up the central part of the flower head in Compositae, each with a pistil and stamens but generally no other conspicuous flower parts. See also: ray floret.

disciform

Round and flattened. See also: discoid.

disclimax

A one-time climax community which has been disturbed by people or their domestic livestock, such as a deciduous forest being replaced by a cropland.

discoid (adj. discoidal)

1. Resembling a disk. 2. In Compositae, a flower head without ray flowers, having disk flowers only.

discolorous

Refers to a leaf which has different colors on the two surfaces.

discontinuity (alt. disjunction)

A gap in the range of a taxon. See also: distribution, disjunct.

discrete

Separate, distinct.

dish garden

A group of plants growing in a bowl or a shallow pot.

disjunct

Separated geographically, especially the population of a restricted area lying outside a main range.

disk

A development of the receptacle at or around the base of the pistil.

disk flower (alt. disc flower)

In Compositae, the tubular flowers of the head, as distinct from the ray.

disk harrows (alt. disk)

A field implement with disk-shaped blades which break up clods and level soil.

disoperation

Interaction between organisms in which one or all are harmed, as competition of maple seedlings, Acer, results in tall weak growth.

disparate

Unequal, not similar.

dispersal

1. The actual passage of disseminules or organisms from one place to another. 2. The history of the movement of a group of organisms, such as the introduction of zebra mussels into the Great Lakes and down the Mississippi River. See also: migration, establishment, spread.

dispersion

1. The pattern of distribution of individuals within a population, especially in prediction of probability. 2. In soil, the breakdown of aggregates, resulting in a single grain structure. Generally the more easily the soil disperses, the more it will erode.

disphotic zone

The depth in bodies of water where light is inadequate for photosynthesis but satisfactory for animal life.

dissected

Cut or divided into numerous lobes or divisions; a deeply cut leaf, the cleft not reaching to the midrib.

dissemination

The process by which propagules or organisms are spread.

disseminule

A plant part that can be easily separated from the parent plant, is dispersed, and can grow into a new plant. See also: diaspore.

dissepiment

A partition in an ovary, pericarp, or fruit.

distal

Towards the apex in position.

distant

Similar to parts that are separated and not overlapping.

distichous

In two vertical ranks.

distinct

Separate; not united; evident.

distributary channels

A system of forking streams flowing away from the main stream and not returning to it, as occurs in a delta or on an alluvial plain.

distribution

1. The geographic range, continuous or discontinuous, of a plant, animal, or community. 2. Dispersal patterns of occurrence of individuals in a taxon from a certain area, such as a) random distribution, poisson distribution, normal distribution; b) nonrandom above normal distribution, contagious dispersal, over-dispersion, hyperdispersion; and c) nonrandom below normal distribution, hypodispersion, or even-spaced distribution. The terms following each letter are synonyms.

distylous

Refers to a flower with two styles.

dithecal

Having two pollen sacs or cells.

diuretics

Herbal medicines taht can promote the flow of urine.

diurnal

Describes flowers which only open in daylight.

divaricate

Widely divergent.

divergence

The circumstance in which seres of similar origin become less like each other as succession moves toward climax. See also: convergence.

divergent

Buds which point away from the twig.

diversion dam

A barrier constructed for diverting part or all of the water in a streambed into a different watercourse.

diversity index

The mathematical statement calculated by dividing the number of species in a specified area by the number of individuals of all of these species.

division

1. A major taxonomic grouping, ranking just below kingdom and above class. In the animal kingdom, it is usually replaced by the phylum. 2. Method of propagation for clump-forming plants through pulling apart fibrous-rooted clumps. 3. The removal of suckers from a parent plant for the purposes of propagation.

divisural line

The line down the teeth of a peristome, through which they split.

document

In botany systematics, this term can refer to herbarium specimens and equipment, as well as to the standard reference to written materials.

document retrieval

A more comprehensive term than 'literature retrieval' since it encompasses unpublished materials such as manuscripts, research notes, films, specimens, as well as published literature. See also: data retrieval.

documentation system

In botany systematics, this term covers the total strategy for identifying, citing, referencing, substantiating and authenticating, validating, verifying, and vouchering information used for a specific purpose in a taxonomic study.

dodder

Any of the annual parasitic wiry twining vines of the genus Cuscuta that lack chlorophyll and have tiny scales instead of leaves.

doldrums

The equatorial belt lying between the two trade wind belts that is characterized by calm or light variable winds and low atmospheric pressure.

doleiform

Shaped like a barrel.

dolomite (adj. dolomitic)

1. A mineral consisting of a calcium magnesium carbonate. 2. Limestone or marble rich in magnesium carbonate.

domatium (pl. domatia)

A small structure located in the axils of the primary veins on the lower surface of leaves in some woody dicotyledons, usually consisting of depressions and being partly enclosed by leaf tissue or hairs.

dominant species

A species that exhibits ecologic dominance or social dominance over adjacent ones. See also: secondary species.

donga

A South African term for a gully with steep sides or a dry watercourse.

dormancy

Temporary cessation of growth.

dormant

In the state of suspended growth.

dormant oil (syn. dormant spray)

Viscous solution containing pesticides and/or fungicides and applied to trees and shrubs in late fall and winter while the plant is dormant.

dorsifixed

Attached at the back.

dorsiventral (alt. dorsoventral)

Having distinct back and front (or upper and lower) surfaces, or placed with reference to the back or front.

double (alt. double-flowered)

Having more than the usual number of petals, often arranged in extra rows.

double citation

The occurence of two names at the end of a taxon, the first name, in parentheses, identifies the author who named the plant originally. The second name CITES the author of the new name.

double digging (syn. double trenching)

A method of inverting soil where the richer, top layer of soil of one trench is placed in the bottom of a subsequent trench and covered with the soil of a lower level.

double fertilization

An exclusive process of angiosperms in which one male nucleus pollinates the egg nucleus to form a zygote, which develops into an embryo, while the other male nucleus joins with two other nuclei in the embryo sac to form endosperm, which can be found in corn, Zea mays, and other grasses.

double-toothed

Each tooth bearing smaller teeth.

double-worked

Twice grafted. The plant consists of the rootstock, an intermediate scion, and the upper scion.

down

An undulating, usually treeless upland plain having sparse soil.

downland

An Australian term for temperate grasslands.

downy

Covered with fine hairs.

downy mildew

A fungus forming grayish downy patches, usually on the underside of leaves.

drainage basin

Any of the largest natural subdivisions of the watersheds of a continent, such as the Mississippi, Columbia, and Colorado basins of North America.

drainage terrace

A graded embankment constructed with a relatively deep channel and low ridge, primarily for the runoff discharge from a hillside.

drawdown

The process of partially or completely lowering the water from a wetland with pumps or other mechanical devices. The purpose of drawdown is to manage vegetation and wildlife.

drepanium

A floral cyme shaped like a sickle.

dried flowers

Desiccated blossoms which retain shape and color over a long period of time, especially for winter arrangements.

driers

Blotters, newsprint or other materials which absorb moisture from plants in plant presses.

drift barrier

An open structure, like a wire fence, constructed across a stream channel to catch driftwood.

drift fence

A fence constructed to prevent livestock from wandering from their allotted range to another one, often used as an extension of natural barriers such as large rivers and cliffs.

drift ice

Parts of icebergs in the open sea beyond the areas of pack ice.

driftwood

Any wood from trees or structures which has floated in water.

drill seeding

Sowing seeds with an agricultural implement which makes furrows into which it drops seeds. See also: broadcast seeding.

drip irrigation (syn. bubbler irrigation)

A method of irrigation where tubes or hoses, sometimes porous, are brought close to plants and water is allowed to trickle out at a very slow, but constant rate.

drip line

The line that could be drawn on the ground under a tree beneath the outermost tips of the branches. Rain flows off the tree at this point, so it is the area where roots congregate and the best point to place fertilizer, water, etc.

drip point (alt. drip-point, alt. drip-tip)

1. A leaf tip with an extension--acuminate, caudate, aristate--from which water drips during wet conditions. 2. A long drooping tip on leaves, particularly those of rain forest trees.

drip zone

The area around the base of a tree that lies below and within the circumference of the branches, etc., which forms its crown.

drooping

Erect at the base, but with the top part bending downward.

drought

A period of dryness; especially one that causes extensive damage to plants.

drought resistance (n. drought resistant)

The capability of an organism to survive extended dry periods with little or no injury. See also: xeric.

drought tolerant

Capable of surviving for extended periods with little or no rainfall.

drumlin

An elongated or oval hill made up of glacial drifts, usually compact and not stratified, and often with the longer sides parallel to the movement of the glacier when the soil is dropped.

drupaceous

Resembling or of the nature of a drupe.

drupe

A fleshy or pulpy fruit with the inner portion of the pericarp (1-celled and 1-seeded, or sometimes several-celled) hard or stony.

drupelet

A diminutive drupe.

dry farming

1. Agricultural operations in semiarid or arid regions without the use of irrigation. 2. A system of cultivation making heavy use of mulch and fallow periods to absorb and retain much of the rainfall.

dry stone

Building in stone without mortar.

dry wall

A wall built without the use of concrete, e.g., a stone wall.

drying frame

A structure, usually collapsible for easy transport, which holds plant specimens open to air and natural or artificial heat for rapid drying, thus preserving color and preventing mildew.

duckfoot

An agricultural implement with horizontal V-shaped blades that cultivate just below the surface of the soil without turning it over or burying crop residues.

duff

The partially decayed leaves, branches, etc., on a forest floor.

dune

A generally unstable mound or ridge of sand built up by winds, most common in deserts and along shores.

dune grass

Various species of Graminae with long roots, adapted to living on dry sand and used to stabilize dunes.

dune sand

1. An area of tiny rock particles accumulated by wind action into mounds or hummocks, generally with little or no vegetation and undergoing continual redeposition. 2. Refers to rock particles with diameters of 0.1 to 0.4 mm. which have been heaped up by the wind, even if found far underground.

dung

Feces, animal droppings, scat.

duplicate

Folded twice.

duriherbosa

Vegetation that has perennial roots, but whose tops die back each winter, like those of grasslands.

durilignosa

Woody perennial vegetation with broad hard leaves, like chaparral.

dust

1. n. A powdered chemical poison to kill insects or disease. 2. v. To apply the powder.

dust devil (alt. dust whirl, syn. remolino)

An intensely whirling column of air caused by a bubble of hot air caught between two cooler layers of air. Dust devils range from a foot to a mile high (30 cm. to 1.5 km.) mostly in arid regions; they spin dust and debris but can also shake houses and slam birds into trees.

dust mulch

Keeping the surface of the soil from caking by repeatedly working it loose, preventing the germination of weed seeds.

Dutch elm disease

A fungus spread by bark beetles that causes wilting and dieback on elms.

dwarf

1. A plant that, due to an inherited characteristic, is shorter or slower growing than normal forms. 2. Dahlia varieties which normally do not produce plant growth over 24 inches in height.

dynamic equilibrium

A system that retains much the same condition because of the action of opposing forces which proceed at more or less equal rates. See also: balance of nature.

dysgenic (alt. eugenics)

Refers to detrimental influences on the genetic properties of a community or population.

dystrophic

1. Relates to or is caused by faulty nutrition. 2. Refers to a lake with high humus material, sparse bottom fauna, and low dissolved oxygen.

earth anchors

Steel pegs with semicircular bases to act as supports for larger trees, tying animals, etc.

earthworm

Any of the terrestrial annelid worms of the class Oligochaeta, especially those of the family Lumbricidae, that aerate and enrich soil.

earwigs

An insect that makes ragged holes flowers and leaves.

ebeneous

Black as ebony.

ecad (syn. ecophene, syn. environmental form)

1. A habitat form. 2. An organism showing somatic adaptations to a certain environment that are not hereditary. See also: phenotype, ecotype.

ecallose

With no callus.

eccentric

Not located at the geometrical center.

ecesis

The establishment of a plant or animal in a new habitat.

echard

Soil water not available for absorption by plants.

echinate

Beset with prickles.

echolocation

1. Acoustic orientation such as that used in sonar. The ability of animals, e.g., bats, to emit high frequency sounds and then determine the whereabouts of themselves and other objects by hearing the corresponding echoes the sounds produce.

eciliate

Lacking cilia.

ecize

To become established, to spread, to invade. See also: ecesis.

ecocline

1. The rate of increase or decrease of a variable character in the adaptation of a species, associated with environmental changes. See geocline. 2. The group exhibiting such a gradient. 3. A gradient of ecosystems along an environmental gradient, including both the gradient of natural communities and the complex gradient of environmental conditions. See also: coenocline.

ecologic dominance

The state in communities in which one or more species, by their size, number or coverage, exert considerable influence or control over the associated species.

ecological amplitude (alt. ecological valence)

The variety of environmental conditions within which an organism can survive and replace itself, or a process can function. See also: tolerance, optimum, pessimum.

ecological bonitation

The numerical statement of well-being of an organism or group during a season or in a specific locality. See also: bonitation, biotic potential.

ecological efficiency

A mathematical statement of the ratio between the energy available to an organism or group or group processes, and the energy actually expended. For example, a bear may use less calories to hunt a rabbit during the summer than the calories gained from the rabbit, but winter hunting expends more than is gained, so it is more ecologically efficient for bears to hibernate. A 10 percent gain is average, 20 percent very good, 5 percent typical of the top of the food chain.

ecological equilibrium

See also: the balance of nature, dynamic equilibrium.

ecological equivalence

The case in which two or more species have enough similarities so that any could replace the other in a specified habitat. See also: ecological amplitude, niche.

ecological equivalent

An organism capable of replacing another in a habitat. See also: ecological equivalence, vicariation.

ecological factor

Any variable of the environment that impacts the life of one or more organisms. May be classified into A: climatic, physiographic, edaphic and biotic factors; or B: direct, indirect, and remote factors. See also: biotic, limiting factor, density dependent factor.

ecological longevity

Life span; the average length of life of a species under stated conditions.

ecological pyramid (alt. pyramid of numbers, Eltonian pyramid)

The concept that in most food chains, the number of individuals decreases at each stage, with huge numbers of tiny individuals at the base and a few large individuals at the top, as displayed by millions of plankton, a moderate number of large fish, and a few eagles.

ecology (adj. ecological)

The study of the relation of organisms to their environments.

ecorollate

Without petals.

ecorticate

Lacking a cortex.

ecospecies

A taxonomic species described in terms of its ecological characteristics, usually including two or more ecotypes capable of interbreeding.

ecostate

Lacking a costa.

ecosystem

An interacting complex of a community, consisting of plants and/or animals, and its environment functioning as an ecological unit.

ecotone

A transition area between two adjacent ecological communities containing characteristic species of each, and sometimes, species unique to the area.

ecotourism

Travel undertaken to areas of unique natural or ecologic quality, or the provision of services to facilitate such travel.

ecotype (syn. ecological race, adj. ecotypic)

A subdivision of an ecospecies that survives as a distinct population through environmental selection and isolation; comparable to a taxonomic subspecies.

ectoparasite

A parasite living on the outside surface of a host, like a tick on a deer.

ectophagous

Refers to an animal that feeds from the outside of a structure, such as a rabbit eating bark from a shrub. See also: entophagous.

ectotrophic

Refers to fungi that grow on the surface covering of roots. See also: endotrophic, mycorrhiza.

edaphic community (alt. edaphic climax)

A climax stage determined by factors related to the soil, pH, drainage, salinity, etc. See also: physiographic climax, biotic climax.

edaphic factor

A condition of the soil that is physical, chemical, or biological that influences organisms growing there. See also: biotic, climatic, ecological factor.

edaphology

The study of soils.

edaphon

1. An organism that lives in the soil, such as a fungus, nematode, bacterium, etc. 2. The aggregate of organisms in the soil, with the exception of plant parts like roots. See also: plankton.

edentate

With no teeth.

edge

The border between two types of habitat, e.g., between forest and meadow, or stream and prairie, with vegetation of each type.

edge effect

The impact of two diverse communities where they abut, such as where a stream adjoins a prairie. See also: ecotone.

edger

A tool used to trim grass and its roots away from sidewalks and curbs.

EDTA (syn. ethylenediaminetetraacetic acid)

The abbreviation for the white crystalline acid often used as a chelating agent.

eelworms

Microscopic organisms that enter the tissues of plants and cause rotting.

effective soil depth (syn. working depth)

The extent to which roots of plants penetrate readily to reach water and nutrients.

effective temperature range

The spread between the highest and lowest temperatures in which an organism can survive and reproduce. See also: ecological amplitude, tolerance.

effluent

The outflow of water or other fluid. See also: influent.

egg

The nonmotile female sex cell (gamete).

egg-shaped

Shaped like an egg, with the broadest portion below the middle.

eglandular

Without glands.

eilliptic

Widest in the middle and tapering evenly to both ends.

elaiosome

A fleshy, protein-rich "food patch" on some seeds or fruits it is attractive to ants and thus aids dispersal.

elasticity

The capability of a strained body to recover its size and shape after deformation.

elater

A plant structure functioning in the distribution of spores, such bands which contract and expand when moistened or dried to disperse spores and the strap-shaped appendages of Equisetum spores.

electrolyte

A soluble substance capable of conducting ions when dissolved.

elements

Organisms typical of a certain region or habitat, but may occur outside of it, such as a group of prairie species found in the eastern part of the united States. See also: ecological factor, vicariation, ecological equivalence.

eligulate

Without strap organs.

ellipsoidal

Widest at or about the middle; margins are symmetrically curved, being narrowed to relatively rounded ends.

elliptic

Narrow at the ends and broad near the center.

elliptical

Oblong with rounded ends.

elongate

Much longer than wide.

eluvial layer

See A horizon.

eluviation

The removal of material from a specified soil horizon by leaching, either in solution or colloidal suspension. See also: illuviation.

emarginate

Having a shallow notch at the extremity.

emasculation

1. In plants, the removal of male flowers or anthers to prevent self-pollination, such as removing tassels from corn, Zea mays, for hybridization. 2. In animals, castration, the removal of testicles, as done with some bulls to turn them into steers to produce tender meat.

embracing

Clasping at the base.

embryo

The rudimentary plantlet within the seed.

embryo sac

A structure inside the ovule of a flowering plant in which pollination occurs, and in which an embryo begins to develop.

embryogenesis

Formation and subsequent development of plumule, radical, and cotyledons in a plant.

embryoid

A mass of tissue that resembles an embryo.

embryotega

A callus near the hilum of certain seeds, which is detached during germination.

emergence

Refers to outgrowths on the surface of an organ, such as warts, prickles, etc.

emergent (syn. emersed)

1. Half uncovered. 2. In mosses, of the capsule, when the perichaetial leaves reach but do not overtop it. 3. An aquatic plant with its lower part submerged and its upper part extending above water.

emergent aquatic plants

Plants rooted in shallow water bottoms with the upper leaves and stems above the water surface.

emersed

Raised above the water.

emetics

Herbal medicines that can induce vomiting.

emigrant

One who moves from one area, emigrates, to live in another. See also: immigrant.

emigration

The process of leaving a locality more or less permanently.

emollients

Herbal medicines that can soften skin.

enantiostylous

Refers to flowers whose stamens bend to the left or right, with the styles in the opposite direction.

enation

An outgrowth on the surface of an organ.

encinal

Refers to a grove or forest of evergreen oaks.

enclosure

An area fenced or otherwise encircled to pen in animals, e.g., sheep. An exclosure is similarly treated to shut out other species, like coyotes, so the same area can be both an enclosure and an exclosure.

encystment

A state of inactivity of an organism surrounded by a protective case; metabolism is lowered while resistance is raised to unfavorable environmental conditions. See also: cyst.

end bud

A bud, or sometimes several, located at the end of the twig.

endangered plant

A species adjudged to be threatened with extermination.

endemic

Confined to a small area; limited in geographic distribution.

endemism

The occurrence of highly adapted plants or animals in an area. See also: endemic.

endocarp

The inner layer of a pericarp.

endochory (syn. endozoochory)

Dispersal of an organism, particularly a seed, by an animal which carries it from one place to another, often in its digestive tract.

endogenous

Growing throughout the substance of the stem, instead of by superficial layers.

endoglossum

A crosswise projection from the back wall of a carpel to make it almost completely septate.

endoparasite (alt. endobiophyta)

The existence of a parasite within an organism, like a tapeworm.

endophytic (n. endophyte)

1. Growing within the tissue of a plant; a plant that grows within another plant, like a fungus endoparasite. 2. A plant that can penetrate a rock, like a lichen.

endoplasma (syn. entoplasm, syn. endosarc)

The inner granular layer of protoplasm in ovum development.

endosperm

The nutritive tissue in a seed of a flowering plant that surrounds the embryo. See also: perisperm.

endospore

An asexual reproductive body found mostly in bacteria.

endostome

The inner row of teeth of a peristome.

endothecium

The inner layers of cells of the capsule.

endotrophic

Refers to fungi that grow within roots. See also: ectotrophic, mycorrhiza.

endozoochore

A propagule like a seed that is dispersed by being carried inside an animal�s body, such as a cherry seed, Prunus, being swallowed by a bird and dropped in feces.

energy flow

The intake, conversion and passage of energy through an organism or ecosystem.

energy transformers

Plants and animals that process and pass on energy, originally transformed from sunlight by plants, from one organism to the next in a food chain. See also: energy flow.

enphytotic

Occurring regularly among the plants of a region, such as an endemic fungus. See also: epiphytotic.

ensiform

Shaped like a sword.

entire

Without toothing or division.

entomophilous

Pollinated by insects.

entophagous

Animals that feed inside of roots, dead leaves, etc. See also: ectophagous.

entropy

The degradation of energy, a measure of the degree of disorder of a system.

envelope (adj. enveloping)

The surrounding part.

environmental clock

The influence of surroundings in initiating activities of organisms or certain processes, such as longer days initiating egg laying in birds.

environmental heterogeneity

The physical or temporal patchiness of the environment, created by disturbances like fire and storms, microclimates, soils, history, and random population variation.

environmental impact

A statement regarding new construction and the consequences it will have on the ecology of the area.

environmental resistance

The limiting influences of environmental factors upon the increase in numbers of individuals in a community. See also: biotic potential, reproductive potential.

Eocene

The second geological epoch in the Cenozoic era--the Tertiary period, that opened about 58 million years ago and lasted for 19 million years.

epappose

With no pappus.

epeirogenesis (alt. epeirogeny, alt. epirogeny)

The deforming of the earth�s crust, producing continents, ocean basins, and great plateaus. See also: diastrophism.

epetiolate

With no petals.

epharmone

An organism which adapted to changes in its environment. See also: ecad, epharmony.

epharmony

The changes of processes or shape of structures by which an organism adapts to an altered environment. See also: adaptation, epharmone, ecad.

ephemeral (syn. transient)

1. Lasting one day, or more broadly, for a short time. 2. An herbaceous, perennial plant which dies to the ground after flowering and setting seed in spring or early summer.

epibenthic

Living on the surface of bottom sediments in a water body.

epibiotic

An endemic surviving from a former habitat; a relic.

epicalyx

A whorl of bracts outside the calyx.

epicarp

The outer layer of the pericarp or matured ovary.

epichil (alt. epichile, alt. epichilium)

The terminal part of the lip in some orchids, distinctly different from the form of the basal part.

epicole (alt. epibiont)

An organism which attaches itself to a host without either benefit or harm to the host, such as lichens on the bark of trees. See also: commensalism, epiphyte, parasite.

epicormic

Describes new growth (buds, shoots, or flowers) borne on the old wood of trees.

epicortical

Outside the bark.

epicotyl

The stem of a seedling between the cotyledons and the first true leaves.

epidemic

The pervasive spread of organisms which are parasitic, predatory, or damaging.

epidermis

The outermost layer of cells covering the plant.

epigeal

Of or relating to the emergence of cotyledons above the surface of the ground. See also: hypogeal.

epilia

A population of air plants, epiphytes. See also: epicole.

epilimnion

The upper layer of a lake which is disturbed by winds, lying above the thermocline. See also: hypolimnion.

epilithic

Growing on rocks.

epinasty (adj. epinastic)

In plant physiology, the state in which more vigorous growth occurs in the upper surface of an organ, such as in an unfolding leaf, causing a downward curvature. See also: hyponasty.

epiorganism (alt. supraorganism)

A natural group made up of similar individuals, like a hive of bees or a stand of maples, Acer. See also: community, population.

epipetalous

Borne on or attached to the petals.

epipetric

Growing on rock.

epiphragm

A membrane covering the mouth of the deoperculate capsule.

epiphyll

An organism that grows on leaves. See also: epiphyte.

epiphyllous

Growing on a leaf, usually through vegetative reproduction.

epiphyte (adj. epiphytic, syn. aerophyte)

A plant growing attached to another plant, but not parasitic; an air plant.

epiphyton

A collection of organisms scattered over surfaces submerged in water, that may later become mechanically associated. See also: lasion, periphyton.

epiphytotic

Common, even epidemic, among plants in general, as some fungus diseases like mildew. See also: enphytotic.

episepalous

Borne on or attached to the sepals.

epispastics

Herbal medicines which can cause blisters.

epistasis

Suppression of the effect of a gene by another, nonallelic gene.

epithalassa

The upper layer of water above the thermocline, where stratification occurs because of water temperature in the ocean.

epithelium

Cellular tissue which covers a surface or lines a tube to assist secretion production and help assimilate nutrients.

epithet

The part of a scientific name designating a species or lower division of a genus. For example, in Cyranthus mackenii var. cooperi, mackenii is the species epithet and cooperi is the variety epithet.

epizoan

An epiphyte animal.

epruinose

Lacking bloom on the surface.

epsom salts

Bitter crystalline hydrated magnesium sulfate, sometimes used as a soil amendment.

equal

Of the same length, as in 'sepals equal petals.' It means that two plants are the same length--not that they are indistinguishable, as when two plants are so inseparable they are called tepals.

equidistant

The same measurement apart.

equilateral

Equal on both sides of an axis.

equitant

Astride; refers to conduplicate leaves which enfold each other in two ranks, alternating one above the other on opposite sides of the stem, as occurs on an iris.

eradicate (n. eradication, syn. exterminate)

To remove entirely; to pull up by the roots.

erecto-patent

Midway between erect and patent.

erect

Vertical or upright

eremean

Belonging to regions of low, irregular rainfall.

erianthous

Having woolly flowers.

ericaceous

Refers to plants of the family Ericaceae that require an acid soil, generally with a pH of 6 or less.

ericoid

Like a heath.

erinous

Prickly, with sharp points.

erose

Irregularly cut away as if gnawed.

erosion (v. erode)

Slow destruction of soil or rock by the action of water, wind, or ice.

errhines

Herbal medicines applied in the nose to promote discharge of mucus.

erumpent

Appearing to be ready to break through.

escape

An exotic plant that has spread from cultivation and grows successfully in the wild.

escarpment (alt. scarp)

A long inland cliff or steep slope formed by erosion, often by waves, or sometimes by a fault.

esorediate

Lacking soredia.

espalier

A plant trained to grow flat against a wall or framework. To train a tree or shrub with its branches growing in a two-dimensional plane, flat against a building or fence.

essential oil

Any volatile plant oil used in perfume or flavorings.

estipulate (alt. exstipulate)

With no bract at the base of the petiole.

estivation

Stagnating or otherwise nonfunctional during the summer months. See also: hibernation.

estrogenic

Herbal medicine that stimulates female hormone production or replaces it with plant hormones.

ethnobotany

The plant lore and agricultural customs of a people; the systematic study of such lore.

ethnopharmacology

The study and practice of medicines used by a people.

ethylene

A colorless flammable hydrocarbon gas occurring in plants, acting as growth regulator and fruit ripener.

etiolate (n. etiolation)

To alter the natural development of a plant by excluding sunlight, often resulting in pale or bleached foliage. Etiolation is one method of layering for propagation; the shaded parts turn white or cream and develop no leaves.

eucamptodromous

Describes leaves having pinnate venation in which the secondary veins do not terminate at the margins but which gradually diminish inside the margin, connected to the superadjacent secondary veins by a series of cross-veins without forming prominent marginal loops. See also: acrodromous, brochidodromous, semicraspedodromous.

Euglenophyta

A taxonomic division containing euglenoids and Euglena. All are single-celled and found mostly in fresh water. They can contract the vacuole and have a single flagellum.

eukaryote

An organism composed of one or more cells containing visibly evident nuclei and organelles, including all organisms except viruses, bacteria, and cyanobacteria. See also: prokaryote.

eusporangiate

Refers to ferns having sporangia with walls thicker than one cell. See also: leptosporangiate.

eusporangium

A thick-walled sporangium originating from several epidermal cells.

eutrophic

Rich in dissolved nutrients, photosynthetically productive and often deficient in oxygen during warm weather.

evanescent

Disappearing at maturity.

even-pinnate

A pinnately-compound leaf lacking a terminal leaflet.

everlastings

Plants with flowers which hold their color and shape when dried.

evolute

Opened, unfolded.

evolution

Organic evolution is any genetic difference in organisms from generation to generation.

ex situ conservation

A conservation method that entails the removal of seed, pollen, sperm or individual organisms from their original habitat, keeping these resources of biodiversity alive outside of their natural environment.

exalate

Lacking an ala.

exalbuminous

Without albumen.

exappendiculate

With no appendages.

exarate

With grooves.

exarillate

Without an aril.

exceed (alt. exceeding)

Refers to parts being compared in size where one is longer than the other.

excentric

Off center.

excrescence

Abnormal development, an outgrowth.

excurrent

1. A growth habit with a single vertical trunk, the branches obviously secondary. 2. Describes a costa running out beyond the lamina of a leaf. 3. Running out, as a nerve of a leaf projecting beyond the margin.

excurved (n. excurvature)

Curved out and away from the central part.

exedra

1. An open or colonnaded recess used for conversation, often semicircular and furnished with seats or a long bench. 2. A semicircular bench with a solid back.

exfoliate

To peel off or shed, as the thin layers of bark.

exfoliating

Cleaving off in thin layers.

exiguous

Small and narrow.

exindusiate

Lacking indusia.

exine

The outer layer of the wall of a pollen grain or spore.

exocarp

The outer layer or skin of a pericarp.

exogenous

1. Grown or made outside the body. 2. Growing by annular layers near the surface, as bark. 3. Produced by growth from superficial tissue.

exostome

The outer row of teeth of a peristotne.

exotic

Not native, from another area.

exotic species (syn. alien species)

A species that is not native to a particular geographic location, but may have become naturalized there.

expanded

Increased in area or size.

expectorants

Herbal medicines which can loosen mucus from the throat.

explanate

Flat, fanned out.

exserted

1. Projecting beyond an envelope, as stamens from a corolla. 2. In mosses, elevated above the surrounding parts of the capsule, when the perichaetial leaves do not reach as high as their base.

exsiccated

Dried.

exstipitate

Lacking a stipe.

exstipulate

Having no stipules.

extant

Still in existence; not extinct.

extensile

Capable of enlargement or extension.

extinct

No longer living; no longer in existence.

extinction (syn. extirpation)

The evolutionary end of a species or the loss of a species in a large area such as a state or country, caused by the failure to reproduce and the death of remaining members of the species.

extirpated

Literally, plucked up by the roots, exterminated. Often used to indicate that a species once lived in an area, and no longer does, usually because of changes in habitat.

extirpation

Wiped out, completely destroyed. Carries the connotation of differing from extinction in that it is more often due to human causes.

extra-axillary

Arising on the side of a stem outside of or opposite to an axil.

extract

A product prepared by removing essential constituents of a plant, such as oils for flavorings.

extrafloral

Beyond the essential parts of the flower, as nectaries, bracts, etc.

extrastaminal

Outside the stamens.

extratropical

Outside the tropics.

extravaginal

Describes a shoot which arises from an axillary bud and breaks through the sheath of the subtending leaf.

extrorse

Facing outward.

exudate (syn. sweat)

Matter oozing from a surface.

exvaginate

Outside the sheath.

eye

1. The center of a flower, if a different color from the rest. 2. A stem cutting with a single bud. 3. The undeveloped bud on a tuber.

eye-spot

A red cytoplasmic structure sensitive to light.

F layer

Sometimes used to designate the upper layer of soil litter whose origin and age can still be determined, although it is partially decomposed. See also: A horizon, H layer, L layer.

F1 hybrid

First-generation cross between two pure-bred strains. These hybrids produce seeds that are not true to type. See also: filial generation.

F2 hybrid

Second-generation cross between two F1 hybrids. See also: filial generation.

faciation

A part of a climax association which lacks some of the dominants of the normal association due to slight differences in environmental fundamentals.

facies

1. A variation of the biotope, differing from the typical conditions in minor ways. 2. A deviation in a community like a dogwood, Cornus, or shrub facies in an oak forest. 3. The top to bottom appearance of a plant, including foliage, flowers, fruit, roots, etc. See also: faciation.

facultative

Capable of functioning under varying environmental conditions, e.g., a parasite which can survive with or without a host. See also: obligate.

facultative apomict

A plant that can reproduce either sexually or asexually (apomixis.)

fairy ring

A circle of mushrooms or toadstools growing from underground mycelium, which is usually surrounded by a ring of vegetation and is rather common in grasslands and sometimes in forests.

falcate

Scythe-shaped; curved and flat, tapering gradually.

fall line

A line connecting the points where rivers leave the uplands as they flow to the lowlands, indicated by sharper slopes and waterfalls.

fallout

The dropout from the air of solid materials, particularly in reference to radioactive dust from nuclear explosions.

fallow

Refers to cropland left standing without cultivation except to destroy weeds and accumulate water and nutrients for a later crop.

falls

Pendulous outer petals, as those found on an iris.

false annual ring

An extra growth ring produced in a season with a drought and then more rain.

family

A group of plants sharing common features and distinctive characteristics and comprising related genera; the taxonomic category above genus and below order.

fan-compound

A compound leaf with leaflets radiating from a single point; palmate-compound.

fan-lobed

Major lobes radiating from a single point; palmate-lobed.

fan-veined

Main veins radiating from a single point; palmate-veined.

fancy

Term used by the International Code of nomenclature for cultivated Plants. It is applied to cultivars, grexes, and hybrids, as opposed to natural species.

fangy

Describes forked roots.

farina

A waxy-appearing substance exuded from glands.

farinaceous (syn. farinose)

Containing starch; powdery, starch-like.

farinose

Covered with a waxy, whitish powder; bearing farina.

fasciation

An abnormal flattening or coalescence of stems or leaf stalks.

fascicle

A close bundle or cluster.

fasciculate

In close bundles or clusters.

fasciculated root

A fibrous root where some of the branches are thickened.

fastigiate

Describes branches that are erect and near together, forming a columnar shape.

father plant

The species from which pollen was obtained to create a hybrid.

fauces (sing. faux)

The throat of a flower in which the petals are united at least at the base, especially when the throat is distinguished in some way such as color, scales, etc.

fauna

A collective term, including all the kids of animals in an area or geologic period.

faunal region

An area with characteristic kinds of animals.

faveolate (alt. favose)

Honey-combed.

favulariate

Finely ribbed, the ribs separated by zig-zag furrows.

feather-compound

Midribs of main leaflets branching from a central midrib at several points in a feather-like pattern; pinnate-compound.

feather-lobed

The main lobes more or less at right angles to the midrib, not radiating from a central point; pinnate-lobed.

feather-veined

Describes leaves whose veins all arise pinnately from a single midrib.

feces

Animal droppings, manure, scats.

fecundity

Productivity of an organism regarding fertility structures, like eggs, sperm, pollen, etc.

feedback

Any partial reversion of the effects of a given process to its source, such as leaves falling to the ground and furnishing calcium for uptake by the roots of the plant.

feeder root

One of the numerous small roots of a plant, through which moisture and nutrients are absorbed from the soil.

felted-tomentose

Woolly and matted, the hairs curling and tangling tightly to the surface.

fen

Low marshy ground containing peat that is relatively rich in mineral salts and is alkaline rather than acidic. It is usually found in the upper parts of old estuaries or around fresh water lakes, with vegetation quite different from that of moors.

fenestrate

Having openings, perforations or translucent areas.

Feng Shui

An ancient Chinese discipline combining town planning, environmental impact, architecture and interior decoration. Time, space, and action are designated to increase energy, harmony, healing, etc.

feral

Refers to an organism that escapes from cultivation or domestication and becomes naturalized.

fermentation

The chemical change of organic substances by organisms, such as yeast turning sugar into alcohol and carbon dioxide.

fern ally (pl. fern allies)

A nonflowering, vascular plant belonging to one of the following classes: Equisetopsida (horsetails) Lycopdiopsida (club mosses, spike mosses, and quillworts) and Rhyniopsida (whisk fern).

ferruginous

Rust-color.

fertile

Capable of producing fruit; or productive, as a flower having a pistil or an anther having pollen.

fertility

1. The reproductive capacity of an organism. See also: fecundity. 2. The property of soil that allows it to provide available nutrients and moisture to plants.

fertilization (alt. fertilisation)

The union of male and female gametes.

fertilizer

Synthetic or natural organic substances providing essential plant foods. It most often includes nitrogen (N), phosphorus (phosphate; P), and potassium (potash; K).

fetid (alt. foetid)

Carrying an unpleasant odor.

fibril

A short simple lateral branch of a lichen.

fibrillate

Finely fibrous or with hair-like lines.

fibrillose

1. Furnished or abounding with fine fibers. 2. Having fibrils.

fibrous

Composed of or resembling fibers. Fibrous tissue: a tissue formed of elongated thick-walled cells.

fibrous root

A root that has no prominent central axis and that branches in all directions.

fibrovascular

Composed of woody fibers and ducts.

fiddlehead

One of the young unfurling fronds of some ferns that are often eaten as greens.

fidelity

The regularity with which a species occurs in certain plant communities, expressed in a five-part scale ranging from the most to least common: 5) exclusive, 4) selective, 3) preferential, 2) companion or indifferent, 1) accidental or stranger.

field border plantings

Vegetation established on the margins of fields to conserve soil and to provide food and shelter for wildlife, like native shrubs. See also: filter strip.

field crops (syn. cash crops)

Agricultural production such as grains, hay, root crops and fiber in contrast to vegetables and fruits. See also: truck crops.

field equipment

Gear necessary to collect botanical specimens in the wild, such as maps, diggers and clippers, trowels, hand lens, collection bottles and bags, insect repellents, cameras, etc.

field expedition (syn. field trip)

A journey planned to collect flora of a specific area or habitat.

field layer

The low stratum of plants like grasses, forbs and dwarf shrubs. See also: canopy layer.

field preservatives

Materials used to hold wet plant samples for long periods of time, or to hold plant specimens in tropical areas. Examples are 2:3 commercial 40 percent formaldehyde and water; 1:2 formaldehyde and 70 percent alcohol; 40-50 percent alcohol; 1-2 percent aqueous solution of oxyquinoline sulfate. Specimens may be dipped, sprayed, or brushed with one of these, then enclosed in an airtight container.

field records (syn. field notes, syn. field data)

A pocket-sized notebook which holds complete data on a field trip, including the precise location of places explored, dates, flora collected with any assigned numbers such as a tube of pollen or seeds, information on such things as a location in shade or sun, insects found on plants, moisture, bloom or fruit and their colors, and nearby plants, etc.

field strip cropping

A specialized strip cropping where crops are planted in parallel bands across a slope but do not follow contour lines; bands of grass or other close-growing species are alternated with the bands of cultivated crops.

field test (syn. field laboratory)

An experiment conducted under regular field conditions, less subject to control than a precise contained experiment.

filamentous

1. Made up of filaments or bearing them. 2. A form of lichen containing filamentous algae and fungi.

filial generation

In hybrid offspring, the first cross is designated as F1; the second cross as F2, etc.

filiform (syn. thread-like)

Thread-shaped; long, slender, and terete.

filmy fern

A fern of shady places with exceptionally thin frond leaflets, usually of the family Hymenophyllaceae.

filter bridge

A land connection that remains in place for a demonstrated period of time, restricted in extent, limiting the kinds of organisms which can migrate over it, such as the Bering Strait in the Pleistocene period. See also: corridor, sweepstakes bridge.

filter strip (syn. greenway, syn. greenbelt, syn. beltway, syn. buffer strip, syn. buffer zone, syn. vegetated filter zone)

A permanent strip of low plantings on the lower side of a field that is sufficiently wide and dense to slow the movement of runoff, allowing deposition of silt on the strip rather than its transport to a stream or pond. See also: field border plantings.

fimbriate (alt. fimbriated, n. fimbriation)

Fringed; having the edge or extremity bordered by slender processes.

fimbrillate

Having a minute fringe.

fine-textured soil

A soil that consists mostly of silt and clay, with little or no sand or gravel.

fines

Materials from rock and organic extraction that are often carried away by the action of wind or water.

fire control line

A designated margin along which a wildfire, if possible, is not allowed to pass; often backfires are started here.

fire hazard

The risk level of a fire starting under prevailing climatic conditions, often simply low, average, or high.

fire towers

Structures in forests which rise above the tree tops and are staffed during fire danger periods.

fireblight

A bacterial disease of rose family.

firebreak

A strip of land where flammable materials have been removed to check or stop a creeping or running wildfire.

firn

Granular snow, usually compacted; a ski term for last year’s snow. See also: neve.

first bottom

The flood plain that is closest to a stream or is at the lowest elevation above a stream; the first to be flooded.

firth

A term commonly used in Scotland that means a long narrow arm of the sea or the mouth of an estuary.

fishway (syn. fish ladder)

A sloping structure over which water is allowed to flow, to help fish in breeding season to ascend a stream which forms a waterfall.

fissile

Easy to split.

fissured

Having deep cracks.

fistular

Hollow and cylindrical.

fitness

The level of adaptation of an organism to its environment.

fitness of environment

The suitability of a habitat for preserving life.

flabellate

Fan-shaped.

flachmoor

Wasteland with a flat to slightly depressed surface, with peaty soils that are poor in salts and have an acidic reaction.

flagellates

Cells with flagella but no cell wall.

flagelliflorous

Bearing flowers at the ends of long, pendulous branches.

flagelliform

Whip-like in shape.

flagellum (pl. flagella)

Tiny whip-like appendage that is capable of movement.

flaky

Bark with loose scales which are easily rubbed off.

flank

The side of anything, like the west flank of a mountain.

flats

Low, exposed land of a lake delta or a lake bottom; or often brushy land along the floodplain of a stream.

fleshy

Succulent or juicy.

flexible

Easily bent or twisted.

flexuose (alt. flexuous)

Zigzag; bending from side to side; wavy; sinuous.

floating-leaved plants

A free-floating plant such as duckweed, Lemna; or one with roots in the water bottom but having leaves that float on the surface like the water lily, Nymphaea.

floccose

Clothed with locks or flocks of soft hair or wool.

flocculate (n. flocculation)

1. To cause to form lumps or masses, as in soil. 2. The rapid precipitation of large amounts of a solute out of a solvent.

flocculation

The coming together of suspended colloidal material or very fine particles like silt, into larger masses called floccules.

flocculent

Resembling wool especially in loose fluffy organization.

floodplain (alt. flood plain)

The almost level land forming the floor on either side of a stream in a valley, often subject to flooding.

flora

All plants as a group; the particular plants of a region.

floral

Belonging to or associated with a flower.

floral cup

A cup-shaped or tubular part of a flower.

floral envelope

The perianth.

floral region (alt. floristic region, alt. floristic area)

An area with a degree of homogeneity of species existing because of similarities in topography, climate, etc., in the region.

floral shovel

A round-pointed shovel.

floral snip

Scissors specialized for delicate jobs, such as harvesting herbaceous flowers.

floral tube

A tube formed in some flowers by the fusion of the perianth and the stamens.

floret

A small flower, usually one of a dense cluster. See also: flowerhead.

floricane

A biennial stem typical of Rubus, which grows the first year, and bears fruit and dies the second year.

floriculture

The cultivation of ornamental plants, especially flowering plants.

floriferous

Flower-bearing; blooming profusely.

florigen

A hormone which appears to be produced in the leaves, then translocated to apical meristems where it initiates the formation of flowers.

florist

One who sells flowers retail, usually obtaining the blossoms from a middle man.

floristic composition

The array of plant species that occurs in a community or region.

floristic element

Species that are characteristic of a designated region but may also occur in a different one, e.g., a midwest united States species growing in the upper levels of the Smoky Mountains is a midwest element of those mountains.

floristic study

A complete listing of the plants from a given jurisdiction, e.g., a state, or from habitats such as lake shores or marshes, or a listing of all of the species within a genus or other delineation.

floristic territory

A geographic area characterized by the common occurrence of a number of more or less endemic species, although other species may be present.

flower

1. The reproductive structure of a flowering plant consisting of a pistil and/or stamen, and usually including petals and sepals. 2. Often applies to the reproductive organs of mosses.

flower bed

An area planted with flowering plants and surrounded by lawn, structures, etc.

flower box (alt. window box)

A container attached to a porch railing or window sill planted with colorful species.

flower bud

The bud which contains a flower or a cluster of flowers.

flower head

A group of florets.

flower induction

The initiation of the production of flowers, possibly stimulated by florigen.

flowering dates

The period(s) of the year when a species can be expected to produce blossoms.

fluctuation

A relatively atypical departure from more average conditions, but still within normal limits.

flume

1. In the united States, a ravine or gorge with a stream running through it. 2. A man-made open conduit, often made of wood or concrete, for the purposes of irrigation, power, etc. It operates by transporting liquids across a stream or depression which intersects the course of the conduit.

flush cut

A pruning cut to remove a tree limb in which the cut is completely flush with the tree. The resulting scar is too large to heal efficiently.

fluted

With rounded, longitudinal grooves or ridges.

flyway

A migratory pathway of birds, like the Mississippi flyway following the Mississippi River.

foehn

A Swiss term for a wind blowing down a mountainside, especially if it is warm for the season. See also: chinook.

fogger

A device used to apply a pesticide in suspension in water or air.

foliaceous

Leaf-like in texture or appearance.

foliage

The leaves of a plant taken collectively.

foliar diagnosis

Evaluation of the nutrients in a plant, or the plant nutrient requirements of a soil, by analyzing the leaves.

foliar feeding (alt. foliar fertilizing)

The process whereby plants are fertilized by application of liquid onto the leaves rather than through the soil.

foliate

Bearing leaves.

folic acid (syn. pteroylglutamic acid)

A member of the B vitamin complex, found mostly in the leaves of plants.

foliolate

Bearing leaflets.

follicular

Like a follicle.

food chain

An ever increasing progression of edibles, from microscopic plankton which are eaten by small animals, which in turn are eaten by larger animals, and so on, up to the largest predator. The animals all die and are digested by fungi and bacteria, starting the chain all over again.

food cycle (alt. food web)

All the interconnecting food chains in a community.

food niche

The location of a particular organism in a food cycle.

food pyramid

A theoretical graphic illustration showing the immense number of producer organisms at the base and the progressively decreasing numbers of herbivores and carnivores toward the peak.

forage acre

A theoretical concept demonstrating the quantity of feed on an acre of land which is totally covered with vegetation and completely utilized under proper management.

forage acre requirement

The number of forage acres needed for the maintenance of X numbers of mature grazing animals for a specified period of time.

forage ratio

A mathematical statement regarding the percentage of a prey species present in the food of a predator species, which is divided by the percentage of the prey species present in the habitat.

forage volume

1. The total parts of plants that can be reached by grazing or browsing animals. 2. A measure of the yield of feed, the total amount produced on a certain range during a year.

foraminifers

Small marine animals with calcareous shells which are perforated with minute holes for extension of pseudopods.

forb

A nonwoody plant other than grass, sedge, or rush. See also: herb.

foredune

A low pile of sand, often held in place by dune grass, bordering the shore of a sandy lake or sea.

forensic

Relating to the application of scientific knowledge to legal problems, as a forensic entomologist helps place time of death by developmental stages of insects on the deceased.

foreshore

That portion of the beach occupied on a daily basis by tides.

forest cover

The living plants and dead organic matter on the floor of a forest, sometimes restricted to only the plants. See also: basal cover, duff.

forest edge

The boundary or ecotone of a forest where it meets with some other kind of vegetation such as a marsh.

forest floor

The deposits of plant material such as dead leaves and branches on the ground in a woodland. See also: duff, forest cover.

forest fragmentation

The continuing splitting of large forested areas by highways and residences, which changes the habitat. It affects the acclimation and persistence of wildlife and indigenous plant species.

forest influences

A total of the effects or reactions of a woodland on the environmental conditions, such as providing duff as compost, and maintaining uniform stream flow.

forest type

A stand of trees that is fundamentally similar throughout and can be predicted to occur elsewhere under comparable conditions. It includes temporary, permanent, climax, and cover types.

forked

Divided into nearly equal branches.

forma (abr. f.)

The rank of taxa below variety; the narrowest taxon; a plant which retains most of the characteristics of the species, but differs in some way such as flower or leaf color, size of mature plant, etc. A forma is added to the specific binomial and preceded by "f.", such as rubra in the epithet Cornus florida f. rubra.

form

A small but constant variation within a population of plants, such as a white-flowered plant in a normally purple-flowered population.

formenkreis

A series of related forms pinpointed geographically that originated entirely or primarily by geographic isolation. See also: speciation, evolution.

fortnight

Two weeks, fourteen nights.

fossorial

Refers to animals that burrow in the soil, e.g., voles.

foundation planting

Those shrubs and flowers planted close to the house which make a smooth transition to the surrounding landscape.

founder principle

The theory that an isolated population, perhaps on an island or cut off in other ways, holds a small number of settlers with a limited gene pool, which is the first step toward new species.

foveolate (alt. foveate)

Honeycombed; pitted.

fox fire

Phosphorescent light caused by a fungus on decaying wood.

fragment

Refers to communities, a stand so small that it lacks sufficient species composition and other characteristics associated with a community. See also: population.

fragmented structure

Refers to a soil composed mostly of particles that exhibit well defined faces and edges. See also: granular structure.

fragrance garden

A garden consisting of flowering plants and herbs noted for pleasant odors. Often used in recreational/educational areas for the visually impaired, and for residential yards used at night.

frass

Debris and fecal matter produced by insects.

free-central

Describes placentation where the ovules are borne on a free-standing central placenta within the ovary.

French drain

A channel leading from an overly wet area or to a dry area to transport water as needed. The deep narrow channel is filled with stone to allow water to pass, but to also provide a firm surface.

frequency (alt. frequence)

1. The level of regularity found in the distribution of individuals of a species in an area, especially in a stand. See also: constancy, stand. 2. A general term for a group of plants with more or less regularity of physiognomy, composition, and habitat. See also: community, association.

frequency class

One of the small groups into which a frequency index of the various species in a stand may be classified.

frequency index

A mathematical expression using the percentage of frequency; e.g., a species inhabiting 16 of 20 sample areas has a frequency index of 80 percent.

friability

Desirable texture of soil that allows it to crumble into small particles rather than large clods.

frigid zone

That part of the earth lying north of the arctic Circle or south of the Antarctic Circle. See also: temperate zone, tropic zone.

frigorideserta

Tundra; cold arctic or antarctic areas, and alpine communities.

fringed

Fimbriate.

fringing forest

A strip of woodland along a stream or body of water. See also: gallery forest.

frondose

Leafy, frond-like.

front

The border between warm and cold air masses at the earth’s surface.

frost

1. A covering of minute ice crystals on a cold surface. 2. The temperature low enough for this to occur. See also: hard frost, light frost.

frost resistance

The capacity for survival of a plant when ice crystals form in the cells. See also: hardening.

frostless season (alt. frost free days)

The time between the last spring frost and the first autumn frost.

fructiferous

Capable of bearing fruit.

fructification

The act or organs of fruiting.

frugivore

An animal that eats fruit.

fruit

1. The mature ovary of a seed plant. 2. Sporangia; often applied to the sporophyte.

fruit harvester

A basket made of wire with curved tips, fastened to a long handle, to catch fruit and pluck it from the ground.

fruit-dot

A sorus.

fruiting spur

On a fruit tree, a short twisted branch with rings around it, which flowers and produces fruit.

frutescent (alt. fruticose)

Resembling a shrub.

fruticeta

Vegetation type made up of scrubby forest.

fruticose

Shrub-like, bushy, with many stems rather than a single trunk; a form of lichen which appears shrubby or hair-like.

fruticose lichen

A lichen with a thallus more than 10 cm. (4 inches) tall, like Cladonia rangiferina, reindeer moss.

fucoid

Resembling a seaweed, especially Fucus.

fugacious

Falling or fading very early; short-lived.

fully double

Flower heads with multiple rows of ray florets; the disc florets are immature and completely covered by the central rays when the flower is at its prime stage.

fully revolute

Rolled backwards with margins touching or overlaping.

fully stocked

Refers to a stand that contains as many trees or other materials of the species and ages as the site can support. See also: overstocked, understocked, carrying capacity.

fumarole

A hole in the earth from which heat and gasses escape under pressure.

fungicide (adj. fungicidal)

An agent to inhibit the growth of, or destroy fungus.

fungivorous

Refers to organisms that eat fungi.

fungoid

Resembling a fungus, mushroom-shaped.

fungus

A nonflowering plant of the kingdom Fungi, all lacking chlorophyll.

funicle (alt. funiculus)

The free stalk of an ovule or seed.

funiculus

The stalk of the ovary in plants.

furfuraceous

Covered with bran-like scales.

furrow dam

A small earth blockade for holding water within a furrow. See also: lister.

furrowed

With channels running lengthwise, including both sulcate grooves and striate thread marks.

fusarium (pl. fusaria)

Any of the pathogenic, imperfect fungi of the genus Fusarium which infect both plants and animals.

fuscous

Dusky, grayish-brown.

fusiform

Spindle-shaped; swollen in the middle and narrowing toward each end.

fusiform root

A taproot which tapers at the top as well as the bottom, like a white radish.

fusoid

Somewhat spindle-shaped.

fynbos

A South African term for sclerophyll vegetation on plateaus and mountains, similar to macchia of the Mediterranean region and chaparral of California.

galactosidase

An enzyme which cuts the glycosidic bond between the sugar galactose and molecule. There are two types, the alpha galactosidases and the beta galactosidases.

galea

A hooded or helmet-shaped portion of a perianth, as the upper sepal of Aconitum, and the upper lip of some bilabiate corollas.

galeate

Helmet-shaped; having a galea.

gall

An abnormal growth or swelling caused by insects, fungus, etc.

A narrow woodland developed along a stream because of constant and sufficient moisture through a grassland or other open vegetation.

galls

Corky swellings.

gametangium

The organ producing the gametes.

gametophyte (syn. gametophore)

That part of the plant which bears the gametes or sexual cells. In mosses, all of the plant except the "#fruit,"# or seta and capsule.

gamopetalous

Having the petals of the corolla more or less united. See also: polypetalous.

gamophyllous

Composed of coalescent leaves or leaf-like organs.

gamosepalous

Having the sepals united.

garden

The proper term for landscaped area or yard. To many Americans, the term refers only to the vegetable garden.

garden hoe

A lightweight hoe for weeding, etc., in home or truck gardens.

garrigue (syn. phrygana, syn. batha)

Stony or sandy--often over-grazed--hillsides, similar to maquis, but hotter and drier still.

gazebo

A free-standing roofed structure usually open on the sides.

gelatinous

Having the consistency of jelly or gelatin.

geminate

Equal, in pairs.

gemmiferous (syn. gemmiparous)

Bearing gemmae.

gemmiparous

With vegetative buds.

gene bank

A facility existing for the ex situ conservation of seeds, tissues, or reproductive cells.

genetic diversity

Variability in the genetic makeup of individuals within or among species; the hereditary variation within and among populations.

genetic dominance

The influence exerted by a dominant gene or allele, like wrinkled seeds being dominant over smooth.

genetic drift

Random changes in isolated populations, or in the frequencies of certain genes, which cannot be accredited to selection, mutation, or migration. See also: natural selection.

geniculate (alt. genticulate)

Bent abruptly, like a knee.

geniculum

A sharply bent joint or node.

genotype

The genetic constitution of an organism, acquired from its parents and available for transmission to its offspring. See also: phenotype.

genus (pl. genera)

A group of closely related species. The taxonomic category ranking above a species and below a family.

geophyte

A plant whose perennating buds are found underground, usually attached to a bulb, corm, tuber, etc.

geotropism

An organism's growth determined by the force of gravity, as roots growing downward and stems upward.

germ cell

A reproductive cell, or gamete, or a cell that will develop into a reproductive cell, such as a spermatocyte or an oocyte.

germ plasm

The cytoplasm of the germ cell, particularly that containing the genetic material.

germination

The sprouting of a plant seed.

germination rate

The proportion of seeds in a given seed lot that are likely to germinate under favorable conditions.

germplasm

The genetic material with its specific molecular and chemical makeup that comprises the physical foundation of the hereditary qualities of an organism.

gesneriad

Any of the mostly tropical plants of the family Gesneriaceae, including gloxina and African violets.

gibberellic acid

A hormone used to promote plant growth, especially that of seedlings, and obtained from the fungus Gibberella fujikoroi.

gibberellin

Any of several growth-regulating plant hormones produced by seeds, mosses, ferns, algae, and fungi.

gibbosity

A swelling of moderate extent and asymmetrical character, chiefly at or near the base of an organ.

gibbous

Protuberant or swollen on one side.

girdle

1. To intentionally remove a circle of bark and cambium from a tree in order to kill it. 2. To encircle tightly, eventually choking of nutrients and causing the death of a plant or limb.

girdling root

A root that has become wrapped around the trunk of the plant which inhibits the uptake of nutrients; usually occurring in plants grown in containers.

glabrate

Somewhat glabrous, or becoming glabrous.

glabrescent

Becoming glabrous in age.

glabrous

Smooth; not rough, pubescent, or hairy.

glade

An open grassy area surrounded by woods.

gland-dot

A tiny gland or pore, usually secreting fluid.

glandular

Bearing glands or of the nature of a gland.

glandular-toothed

Teeth that bear glands.

glaucescent

Somewhat glaucous, lightly coated with a fine bloom.

glauconite

A greenish mineral consisting of a silicate of iron, magnesium, aluminum or potassium found in greensand and often used as a fertilizer or soil supplement.

glaucous

Bluish white; covered or whitened with a very fine, powdery substance.

globose

Globe-shaped.

globular

Spherical or nearly so.

glochid

A barbed hair or bristle.

glomerate

Compactly clustered.

glomerule (adj. glomerulate)

A small compact cluster.

glucose

A monosaccharide sugar widely found in plant and animal tissue.

glumaceous

Furnished with or resembling glumes.

glume

A chaff-like bract; specifically one of the two empty chaffy bracts at the base of the spikelet in the grasses.

glutinose (alt. glutinous)

Viscid, sticky.

glycosidic bond

A bond between a sugar and another organic molecule by way of an intervening nitrogen or oxygen atom.

Golgi complex (syn. Golgi apparatus, syn. Golgi body)

A cytoplasmic organelle that consists of a stack of smooth membranous saccules and associated vesicles and that is active in the modification and transport of protein.

grade adjustment

Changing existing levels of ground areas.

grader (alt. roadgrader)

A truck which smooths the surface of gravel roads and raw soil.

graft

To insert a section of one plant, usually a shoot, into another so that they grow together into a single plant; the plant formed from grafting.

graft chimaera (alt. graft hybrid)

The mingling of tissues belonging to the stock and scion through grafting in a nonsexual manner. These are designated in formulae by a crucifix type cross which appears as "_", e.g., _Laburnocytisus adamii (Laburnum anagyroides _ Chamaecytisus purpureus).

grafting

Method of propagation for trees and shrubs by inserting a section of one plant, usually a shoot, into another so that they grow together into a single plant.

graminaceous

Related to grain-bearing plants.

granular structure

Refers to a soil composed mostly of particles that exhibit rather indistinct faces and edges. See also: fragmented structure.

granulose

Composed of or appearing as if covered by minute grains.

granum (pl. grana)

Structures in chloroplast that consist of thylakoids.

grass catcher

A container fitted onto a lawn mower to catch grass clippings while mowing.

gravitational water

Water held in large pores in soil that drains away or leaches when underdrainage is free.

gray mold

A fungus disease characterized by the gray hairy appearance of affected parts.

graze

1. To feed on grasses and forbes. 2. Grasses and forbes.

green drought

A weather term describing a period of enough rain to keep shallow-rooted plants alive, although the water table continues to recede.

green manure

The plowing under of living plants so that their decay will increase the humus of the soil.

greenhouse

An enclosed structure, usually made of glass (to trap solar radiation), that allows for the regulation of temperature and humidity and is used to propagate and grow plants.

greensand

A sand or sediment that consists largely of dark greenish grains of glauconite, usually mixed with clay or sand.

gregarious

Growing near together or clustered, but not in close tufts or mats.

grex

A group name for all plants derived from crossing the same two or more parent species; the herd or hybrid swarm.

grooved

A general term for sulcate or striate.

grotto

An artificial recess or structure made to resemble a natural cave, often having running water.

ground layering

Another name for tip layering.

groundcover

A plant with a low-growing, spreading habit, grown specifically to cover the ground.

groundwater

Subsurface body of water body in the zone of saturation; That portion of the water beneath the surface of the earth that can be collected with wells, tunnels, or drainage galleries, or that flows naturally to the earth's surface via seeps or springs.

group

An artificial category between species and cultivar used to designate a collection of cultivars with similar parentage.

growth regulator

A chemical that sp.s or slows plant growth or maturation.

grub hoe

A heavy weight hoe for digging roots, etc.

guard cells

The two cells that bound a stoma and by opening and closing allow gas exchange.

guard petals

The outer petals of a rose, especially those that are larger than and also enclose the inner petals.

guides

A term applied to the large parenchyma cells seen in the cross-section of the costa of many Dicrana.

gulch

Western U.S. term for a deep cleft, especially one that is formed following a torrent; a ravine. See also: arroyo, gully, valley.

gully (adj. gullied)

A miniature valley eroded by water. See also: ravine, valley.

guttation

1. The formation of drops of water on plants from moisture in the air. 2. The exudation of liquid water from the uninjured surface of a plant leaf. 3. The process of water being exuded from hydathodes at the enlarged terminations of veins around the margins of the leaves.

gymnosperm

A seed plant that bears naked seeds, i.e., seeds without ovaries. These include conifers, cycads, ginkgos, and ephedras.

gymnospermous

Bearing naked seeds, without an ovary.

gymnostomous

Without a peristome.

gynandrium

A structure in which the stamens are attached to the pistil.

gynobase

An enlargement or prolongation of the receptacle bearing the ovary.

gynobasic

Describes a style arising from the base of the gynoecium.

gynodioecious

Having both bisexual flowers and female flowers, but on separate plants. See also: dioecious.

gynoecium

The pistil or pistils considered as a group.

gynomonoecious

Refers to a plant that produces both perfect flowers and female flowers.

gynophore

A stalk bearing the gynoecium above the level of insertion of the other floral parts.

gynosporangium

The receptacle in which gynospores are developed.

gynospore

One of the larger (female) reproductive bodies in the Isoetaceae, etc.

gynostegial corona

The collective term for the staminal and interstaminal coronas (in Asclepiadaceae), both of which are associated with the gynostegium. See also: staminal corona, interstaminal corona.

gynostegium

The crown of united stamens in milkweeds, Asclepidaceae.

gynostemium

The compound structure resulting from the union of the stamens and pistil in the Orchidaceae.

gypsum

A mineral consisting of hydrous calcium sulfate that is used as a soil amendment to add sulfur and calcium and counteract salt damage. It is added to cement to regulate setting.

h & s

The abbreviation for the height and spread of a plant.

habit

The general appearance of a plant.

habitat

The natural dwelling place of an animal or plant; the type of environment where a particular species is likely to be found.

haft

Narrow stalk-like base to some petals, as those on irises.

hair

1. An epidermal outgrowth composed of a single elongated cell. 2. In lichens, a multicellular outgrowth from the cortex.

hairy

Covered with hairs; pubescent, hirsute, etc.

half-inferior

Describes an ovary partly below and partly above the level of attachment of the perianth and stamens.

halophyte

1. A plant adapted to living in highly saline habitats. 2. A plant that accumulates high concentrations of salt in its tissues.

hamate (syn. hamulose)

Curved like a hook.

hand axe

A similar tool intermediate in size between a hatchet and an axe.

hapaxanthic

Reproducing once only at the end of the plant's life.

haptotropism (adj. haptotropic)

An orientation response of an organism to stimulation by touch.

hard construction (alt. hard landscaping)

The nonliving elements of a landscape installation, made of wood, brick, concrete, etc.

hard frost

A frost where both the air and the soil has dropped below freezing. Many plants can survive a light frost but cannot survive a hard frost.

harden off

To gradually accustom a plant to more difficult living conditions, e.g., moving a plant from the greenhouse to the partial shade of a tree before planting it in a garden.

hardening

1. The process of gradually taking plants into a harsher environment, e.g., from the hothouse to the garden. 2. The term can also mean sustaining a plant from summer to winter, which may include a three-staged process: 1) phytochrome clocks signal the shortening days with a color change. 2) Growth ceases, carbohydrates are transported to the roots, and abscisic acid forms at the union of leaf and stem, dropping the leaf and healing the wound. The dropped leaves serve as mulch and protect the roots from excess cold in the winter, while cell walls toughen. 3) A smooth ice forms around the cells without rupturing them, a process called vitrification.

hardiness

The ability of a plant to withstand winter cold and summer heat.

hardpan

A layer of soil sufficiently clogged with clay or other particles which often prevents the penetration of water and shrub or tree roots.

hardscaping

Man-made objects of a landscape as opposed to natural objects like plants and streams.

hardware cloth

A metal fabric that is more coarse than a window screen but finer than fencing.

hardwood

A term applied to broad-leaved trees as opposed to conifers.

hardwood cutting

Cutting taken from a mature woody stem for the purpose of propagation.

hardy

A term used regarding plants that describes their ability to withstand cold. It does not mean that the plant is long-living, pest resistant, or drought tolerant.

harrow

A field implement with semicircular teeth that breaks up clods and levels soil. 2. To break up and level the soil surface by dragging over it an implement of the same name designed for that purpose.

hastate (syn. halberd-shaped)

Like an arrow-head, but with the basal lobes pointing outward nearly at right angles.

hatchet

A short axe.

haustorium

A specialized absorbing structure of a parasitic plant through which it obtains chemical substances from its host.

1. A dense cluster of sessile or nearly sessile flowers on a very short axis or receptacle; heart-shaped. 2. Ovate with two rounded lobes and a sinus at the base; commonly used to define such a base. 3. The number of animals, e.g., 40 horses, that would be counted by a farmer/rancher as 40 head of horses, or merely 40 head.

head back

To cut back the main branches of a woody plant severely.

heading back

Cutting a branch back to a bud or side branch to increase the number of shoots, making the plant thicker and bushier.

heartwood

The harder and often darker colored wood that forms the interior of a tree trunk or branch.

heath (alt. heathland)

An extensive area of rather open uncultivated land usually with poor coarse soil and covered with low shrubs, such as those of the genus Erica; a moor.

heavy soil

An imprecise term which refers to soil in which the particles are packed closely together with little air or water available to the roots of the plant.

hedge

A fence or boundary formed by a dense row of shrubs or low trees and often given a formal appearance by frequent trimming.

hedge shears

Specialized heavyweight scissors for shaping woody plants into hedges.

hedgerow

A row of shrubs or trees enclosing or separating fields, often on a low berm of earth.

heel

The portion of old wood at the base of a cutting.

heel in

To temporarily store plants with their roots in moist soil or sawdust to hold them for several days or weeks until they are able to be planted properly.

heirloom garden (syn. antique garden)

A garden created using plants that were in cultivation in the past, usually from a particular period.

heirloom plant

A plant that was developed and in cultivation sometime in the past.

helicoid

Having the shape of a flattened coil, often describing a cyme.

heliophilous

Adapted to, or capable of, growing in full sunlight.

hemiepiphytic

Remaining rooted in the ground but climbing tree trunks.

hemiparasite (syn. semiparasite)

A parasite which lives on and derives part of its nourishment from its host, but also conducts photosynthesis; for example, the mistletoe.

hemostatic

Herbal medicine that can stop bleeding.

hemp

1. The course fibers used to make cordage derived from plants of the genus Cannibis, or other similar plants. 2. A plant of the genus Cannibis.

herb garden

A garden consisting of culinary and/or medicinal herbs and often having an ornamental design.

herbaceous

1. Having little or no woody tissue; leaf-like in color and texture. 2. Refers to a plant which dies back to the roots each year during winter, as opposed to a plant which remains green all winter.

herbal

1. A book about herbs, usually illustrated. 2. Of, or relating to, herbs.

herbalism

The cultivation, collection, study and use of herbs, particularly for medicinal purposes.

herbalist

One who practices herbalism.

herbarium

1. An organized and cataloged collection of plant specimens. 2. A specialized room or building with constant levels of temperature, moisture and restricted light where plant samples are stored in a designated pattern in large light proof cabinets, allowing samples to remain useful and to be retrieved for study and comparison for centuries.

herbarium glue (alt. herbarium paste)

An adhesive which minimizes cracking, discoloration, and shattering with age, used in fastening plant specimens to the herbarium sheet.

herbarium sheet

Lightweight white card stock used as backing for herbarium specimens, in a standard size of 11 X 16 inches (28 X 40 cm.).

herbicide

A substance that is fatal to plants, or to selected plants.

hermitage

A usually small building provided for contemplation, especially of nature.

hesperidium

A relatively large fruit, pulpy inside with a hard rind outside, such as citrus fruits; technically a berry.

heteroblastic

Describes a plant which has adult parts distinctly different in form from the juvenile parts.

heterocarpous

Producing more than one kind of fruit.

heteroecious

Parasitic on alternating hosts; starting life on one organism, then affecting a second species.

heterogamete

Either of a pair of gametes that differ from each other in shape, size, or behavior, usually occurring as large nonmotile oogametes and small motile sperms.

heterogamous

Bearing two kinds of flowers.

heterogamy

The union of recognizably male and female gametes.

heteromallous

Turned in different directions.

heteromorphic (alt. heteromorphous)

With different forms during the life-cycle; e.g., a fern with the sporophyte different in form from the gametophyte.

heterophyllous

The presence of two or more distinct leaf shapes on a single individual.

heterostyly (adj. heterostylous, adj. heterostyled)

A species in which flowers are similar except that the stigmas and anthers are held at different levels relative to each other, because style length differs between plants. See also: homostylous.

heterotrophic

An organism that requires chemical energy from already formed organic molecules; dependent on organic food made by photosynthetic plants.

hexaploid

Having six sets of chromosomes.

high analysis fertilizer

A powder containing large quantities of nutrient elements.

high-centered

Having the central petals longest; the classic hybrid tea rose form.

higher taxa

Those names ranking above the species level, e.g., genus, family, order, etc.

hillock

A small hill. See also: knoll.

hilum

The scar or point of attachment of the seed.

hip

The closed and ripened receptacle of a rose which contains the seed.

hippocrepiform

Horseshoe-shaped.

hirsute

Pubescent with rather coarse or stiff hairs.

hirsutulous

Slightly hirsute.

hirtellous

Minutely hirsute.

hispid

Beset with rigid or bristly hairs or with bristles.

hispidulous

Minutely hispid.

hoary

Grayish-white with a fine close pubescence.

holocoenotic

The theory that environmental factors act as a whole or aggregate in their effect upon organisms.

holotype

One pressed herbarium specimen designated by the author as the plant on which the description and name are based. See also: isotype, lectotype, syntype, topotype, nomenclatural type, neotype.

homeopathic

Herbal medicines using the system of homeopathy founded in the 1700s. The theory is that 'like cures like' so minute doses can cure; for example, acid will cure an ulcer.

homochlamydeous

Refers to a flower in which sepals and petals are so similar that all are called tepals.

homogamous

Able to bear just one kind of flower.

homologous

Refers to organs or parts that are similar in form or function.

homology (pl. homologies)

The study of structural similarities that indicate actual physical relationships in which species with the same ancestors retain many of the same traits. See also: convergence.

homomallous

Turned in the same direction.

homomorphic

Shaped the same.

homonym

A scientific name given two or more times to plants of the same taxonomic rank but which are quite distinct from each other. See also: basionym, synonym, tautonym, autonym.

homosporous

Having spores of a single appearance and behavior.

homostyly (adj. homostylous, adj. homostyled)

A species in which the flowers have stigmas and anthers held at the same level relative to each other on all plants. See also: heterostylous.

honeydew drip

The sticky mess on your car after parking under trees which have aphids or other sucking insects infesting the tree. Certain ants and fungi also feed on the honeydew.

hormone

A biochemical product of a specific cell or tissue that causes a change or activity in a cell or tissue located elsewhere in an organism.

horny

With a texture which is hard and brittle, but having a fine texture and is easy to cut.

hort.

A term used in a botanical name to indicate that it is not a properly accepted binomial, but is a name used by gardeners and nurseries, perhaps published, but in nursery catalogs rather than scientific journals. It can stand for three terms: hort., meaning "of the garden;" hortorum, meaning "of gardens;" or hortulanorum, meaning "of gardeners." All three are abbreviated hort., and are never capitalized so as to avoid being mistaken for an author's name.

hortus conclusus

An enclosed garden, as that of a monastery. in art, a representation of the Virgin and Child in a fenced garden; from the latin, "enclosed garden". See also: hortus deliciarum.

hortus deliciarum

A walled garden, like the hortus conclusus, but geared more toward the pleasure of its ownsers and more secular in its motifs; from the latin, "pleasure garden".

hortus fenestralis

A window garden; a window box in the form of a miniature greenhouse; from the latin, "window garden".

hortus siccus

A collection of dried and pressed plants, often arranged in book form; an herbarium; from the latin, "dired garden".

hose-in-hose

With one perfect corolla inside another.

hot caps

Paper or plastic tent covers used to protect small plants from damaging weather conditions.

hotbed

An outdoor pit enclosed with a glass roof and heated by fermenting material, hot water pipes, or electric cables.

houseplant

A plant which can be grown indoors, usually for decorative reasons.

ht.

Abbreviation for plant height.

humate

A salt or ester of a humic acid.

humectant

A substance which promotes retention of moisture; a moistening agent such as crystals of polymer hydrogel, which take up water, releasing it slowly for the roots of thirsty plants.

humidistat

An instrument for measuring, sometimes controlling, the amount of water vapor in the air.

humidity (adj. humid)

The moisture in air.

humidor

A tightly closed container which holds a constant level of moisture in the interior, such as for long-term preservation of seeds or storage of fruits and vegetables.

hummock

A mound rising above the surrounding land, usually overgrown with vegetation.

humus (adj. humic)

Partly or wholly decomposed vegetable matter.

husk

The outer layer of certain fruits like walnuts Juglans, as an outgrowth of the perianth or involucre.

hyalescent

Translucent.

hydathode

An epidermal structure specialized for the secretion or exudation of water.

hydration

The reaction of cement with water to form a chemical compound.

hydraulic seeding

A method of planting grass seed by spraying it in a stream of water, which may contain other materials such as mulch or plant food.

hydric

Of, or adapted to, an extremely moist habitat.

hydromulch

The process of mixing grass seed with water and mulch for spraying onto bare soil directly.

hydrophyte (adj. hydrophytic)

A plant adapted to growing in water, waterlogged soil or on a substrate that becomes inundated on a regular basis.

hydroponics

Raising plants in a totally soilless environment. Plants are grown directly in water with nutrients added as necessary, usually in a greenhouse or under artificial lights.

hydrotropism

The growth of an organism or a part, such as a root, in response to the presence of water.

hygroscopic

1. Altering form or position through changes of moisture. 2. Readily absorbing water and thereby altered in form or direction. Hygrometric is sometimes used with a similar meaning. 3. Pertaining to water that is electrostatically bound to the surface of dirt particles and is therefore unavailable to plants.

hylea

The primeval forest.

hypanthium

A cup-like base of a flower to which the stamens, sepals and petals are attached.

hypertensive

Refers to an herbal medicine that can elevate blood pressure.

hypha (pl. hyphae)

The microscopic, multicellular, nonphotosynthetic filaments of fungi and seaweeds.

hypochil

The (often fleshy or otherwise modified) basal portion of the labellum or lip in Orchidaceae.

hypocotyl

The part of the stem of an embryo or young seedling below the cotyledons.

hypocrateriform

Salverform; a tubal flower flaring out into a flat top.

hypodermis

A layer of cells immediately internal to the epidermis.

hypogeal

Of or relating to the emergence of cotyledons below the surface of the ground. See also: epigeal.

hypoglycemic

1. Refers to herbal medicines that can lower blood sugar. 2. A patient with low blood sugar.

hypogynous

Situated on the receptacle beneath the ovary and free from it and from the calyx; having the petals and stamens so situated.

hypolimnion

The lowest layers of a body of water, below the thermocline, where water does not circulate freely.

hyponasty (adj. hyponastic)

In plant physiology, the state in which more vigorous growth occurs in the lower surface of an organ, such as a young fern frond, causing an upward curvature. See also: epinasty.

hypophysis

A swelling of the seta immediately under the capsule.

hypotensive

Refers to herbal medicines that can reduce blood pressure.

hysteranthous

Refers to plants that have flowers develop before the leaves.

idioblasts

Specialized epidermal cells which produce slime or gum.

illegitimate

Refers to a name published validly, but not satisfying one or more articles of the Code of botanical nomenclature or the Code of Nomenclature for cultivated Plants.

imbricate

Overlapping, either vertically or spirally, where the lower piece covers the base of the next higher, or laterally, as in the aestivation of a calyx or corolla, where at least one piece must be wholly external and one internal.

imbricated

Closely overlapping each other like the tiles of a roof.

immersed

1. Covered up; when related to mosses, refers to the capsule when the perichaetial leaves project beyond it. 2. Growing wholly underwater.

immigrant

One who moves or immigrates into an area. An animal is an emigrant when leaving one area, but the same animal is an immigrant when moving into the new area.

imparipinnate

Having an uneven number of pinnae; lacking a terminal pinna. See also: paripinnate.

imperforate

Lacking holes.

impressed

Bent inward, hollowed, or furrowed as if by pressure.

in vitro

Outside the living body and in an artificial environment, as a tissue culture.

incised

Cut sharply and irregularly, more or less deeply.

included

Not at all protruded from the surrounding envelope.

incompatible

Refers to plants that will not form a lasting union at a graft.

incomplete flower

Lacking one or more whorls, i.e., sepals, petals, stamens, or carpels, of the complete flower.

incrassate

Thickened, often relating to cell walls.

incumbent

Describes cotyledons lying with the back of one against the radicle.

indefinite

Inconstant in number or very numerous.

indigenous

Native and original to the region.

indumentum

A massing of fine hairs, glands, or prickles.

induplicate

Having edges or margins folded inward.

indusiate

Bearing indusia.

indusium (pl. indusia)

The thin, scale-like covering of immature sori.

industate

Provided with an indusium.

inerm (alt. inermous)

Unarmed, no prickles, thorns, teeth, etc.

inferior ovary

With the flower parts growing from above the ovary; one that is adnate to the calyx.

inflated

Bladdery; applied to the alar cells of leaves when enlarged much beyond the size of the neighboring cells.

inflexed

Bent inwards.

inflorescence

The flowering part of a plant, and especially the mode of its arrangement.

influent

1. An organism which sways interactions within a community but is not a dominant species; one which influences. 2. The flow of water from a stream into a body of water, especially subterranean storage. See also: effluent.

infra-

As a prefix, denotes below.

infrageneric

Refers to any taxon of a rank below that of genus, such as species, variety, cultivar, etc.

inframedial

Below the middle.

infraspecific

A taxonomic group within a species, such as a subspecies.

infructescence

The grouping or arrangement of fruits borne on a plant.

infundibuliform (syn. infundibular)

Shaped like a funnel.

inoculant (syn. inoculum)

The material used in an inoculation.

inorganic

1. Being or composed of matter other than that from a plant or animal. 2. Not arising from natural growth; artificial.

inorganic fertilizer

A powdered or liquid chemical mix of nutrients which does not contain carbon.

insect vectors

Bugs that carry and distribute disease-causing microorganisms.

insectivorous (n. insectivore)

Feeding on insects.

inserted

Attached to or growing out of.

integrated pest management (abr. IPM)

A philosophy of pest management based on the idea of using the least dangerous course first; stresses the use of natural controls, such as insect predators, over the use of chemical pesticides.

integument

An outer covering or coat.

inter-

As a prefix, denotes between or among.

intercalary

Of a meristem situated between the apex and the base.

intercalary growth

Growth in the tissue between the apex and the base.

intercalary inflorescence

An inflorescence that either arises in an internodal position, or one originally terminal but ceasing to be so when vegetative growth subsequently resumes from the stem apex.

interfoliaceous

Between the leaves of a pair, as the stipules of many Rubiaceae.

intermediate

1. Refers to a grafting scion which is attached at both ends either simultaneously or successively. 2. Refers to hybrids apparently combining the characters of both of their parents in equal measure and standing midway between them.

internode

The portion of a stem between two nodes.

interpetiolar

Describes a stipule located between the petioles of two opposite leaves. See also: intrapetiolar.

interrupted

Describes an inflorescence with the flowers unevenly distributed along the axis, with conspicuous gaps. Also describes the fertile frond of some ferns with the clusters of sporangia similarly arranged.

interspecific

Refers to hybrids between two separate species of the same genus.

interstaminal corona

The fleshy lobes, often connate into a tube, attached to the base of the staminal column in the interstaminal areas of members of the family Asclepiadaceae. See also: gynostegial corona.

intertidal

The shore zone between high and low tides.

intra-

As a prefix, denotes within or inside.

intramarginal

Within and near the margin.

intrapetiolar

Describes a stipule located between a petiole and the stem. See also: interpetiolar.

intricate

Tangled.

introduced

Brought intentionally from another region for purposes of cultivation.

introgression

The formation of a range of intermediate plants by hybridization among parents and progeny.

introrse

Turned inward or toward the axis.

invaginated

Inside a sheath.

invalid

Refers to scientific names published with incomplete information or in an invalid publication.

invasive

Spreading aggressively from the original site of planting.

involucel

A secondary involucre, as that of an umbellet in Umbelliferae.

involucellate

Having an involucre.

involucral

Belonging to an involucre.

involucrate

Having an involucre.

involucre

A circle or collection of bracts surrounding a flower cluster or head, or a single flower.

involute

1. Rolled inward. 2. With margins of ray florets rolled forward along their longitudinal axis. When fully involute, the margins touch or overlap so only the reverse of the floret is visible.

iron chelate (alt. chelated iron)

A powdered compound used as a soil additive to boost the amount of iron available to plants.

irregular

1. Varying in form. 2. Asymmetrical.

irregular flower

Describes a flower showing inequality in the size, form, or union of its similar parts.

irrigation

The provision of water to plants to supplement rainfall. See also: drip irrigation, center pivot irrigation.

isidia

Finger-like outgrowths from the upper cortex of a lichen.

isodiametric

Having equal diameters.

isogamy

The union of equal gamete.

isolateral

Having upper and lower surfaces which are similar in form.

isomorphic

Having a similar form, but being genetically different.

iteroparity

Refers to an organism that has multiple reproductive seasons over its lifetime. See also: semelparity.

jointed

1. With nodes on the stem. 2. Having obvious, thickened areas between cells.

jugate

Paired, with prefixes for the number of pairs; bijugate would be two pairs.

jugum

A pair.

julaceous

Smooth, slender, and cylindric; like a catkin or a worm.

junceous

Rush-like.

juvenile

Young; not adult.

karyoevolution

Changes in the chromosome set of a number or structure occurring through evolutionary change.

karyotype

Characterization of the chromosome set of an individual or group, described in terms of number, length, centromere position, etc.

katabolism

The process of breaking down protoplasm with the liberation of energy and the formation of simple substances.

kelp

Any of various large brown seaweeds, sometimes used to enrich poor soil.

kernel

The nucleus of an ovule or seed; everything inside the coat.

kingdom

One of the primary taxonomic categories into which natural objects are commonly classified. There are currently five kindoms used: Plantae, Animalia, fungi, Monera (bacteria) and Protista (protozoans, some types of algae, etc.).

kitchen garden

A garden where vegetables, fruits, and herbs are grown for use in cooking.

knees

When growing in a swamp, the above-water spongy roots of cypress, Taxodium. These provide air to the interior systems of the tree.

knot garden

An elaborately designed garden consisting of flowers, herbs, and/or low shrubs arranged in intricate, geometric, knot-like patterns when seen from above.

knotted

Having nodes or lumps.

krummholz (syn. elfin forest)

Scrubby, dwarfish growth of trees, often forming a distinctive zone at the tree line of mountains.

kwongan

The sclerophyllous vegetation of the sand plains of south-western Western Australia.

labiate

Lipped; belonging to the Labiatae.

labriform

Lip-shaped.

labyrinthiform

With complicated sinuous lines or winding passages.

lacecap

A flattop inflorescence in which the outer flowers are larger than the inner ones, and the outer are sterile.

lacerate

Irregularly cleft as if torn.

lachrymiform (alt. lacrymiform)

Tear-shaped.

laciniate

Slashed; divided into narrow pointed lobes.

laciniated

Describing dahlias with the split or fimbriation in proportion to ray floret length, and no less than 1/6 of ray floret length, there should be a twisting in the area of the split involute or revolute ray florets, to give an overall fringed effect.

lactifer (alt. lacticifer)

A latex duct which may or may not produce the milky sap.

lactiferous (alt. lacticiferous)

Describes a plant with a milky sap; producing latex.

lacuna

A cavity or gap, usually referring to one found in tissue.

lacunose

Pitted.

lacustrine

Refers to, produced by, or formed in a lake. Lacustrine wetlands are those reaching into a lake and acted on by waves and currents.

laevigate

Smooth, polished.

lageniform

Shaped like a bottle or flask.

lagoon

A relatively shallow pond, sound or lake, especially one connected to the sea.

lake plain

The nearly flat bed of an extinct lake or the lowland surrounding an existing lake.

lake senescence

The aging process of a wetland or lake that results from excess sediment and vegetation.

lamella (pl. lamellae)

1. A thin flat plate or laterally flattened ridge. 2. The acid crystals of lichens shaped in this way.

lamellate (alt. lamellose)

Composed of or arranged in layers or thin plates; having lamellae.

lamina

A blade; the leafy portion of a frond.

laminal

Superficial on the surface of thalli or lobes of lichens.

lanate (alt. lanose)

Woolly.

lance-shaped

Elongate in shape, broadest below the middle and gradually rowed toward the tip.

lanceolate

Shaped like a lance-head, several times longer than wide, broadest above the base and narrowed to the apex.

landlocked property

A parcel of real estate which does not border any road for access.

landraces

Crop cultivars or animal breeds that evolved with, and has been genetically improved by, traditional agriculturalists, but has not been introduced in modern breeding practices.

landscape architect

A person trained in the location of landscape elements for human use and enjoyment. It involves the placement of structures, traffic flow, and plantings.

landscape architecture

The design of outdoor space for maximum enjoyment.

landscape contractor

A company or individual performing landscape installations.

landscaper

An improper term applied to anyone doing landscape work. Often the person is untrained.

language of flowers (alt. symbolism of flowers)

A complex code under which each species of flower, even individual colors of that species, carries a meaning or message.

lanose (alt. lanate)

Woolly.

lanuginose

Nearly lanate, but with shorter hair.

lasion

A periphyton in which the organisms are densely populated and are interdependent. See also: epiphyton.

lateral

Side shoot, bud, etc.

lateral cane

Any cane growing from a main cane.

lath

In gardening, any overhead plant protection structure that reduces direct sunlight or protects plants from frost. Wooden strips called laths, wired together in snow fences, were originally used for that purpose.

latiseptate

Having broad partitions. See also: angustiseptate.

latrorse

Turned sideways.

lawn

An area of cultivated and mown grass.

leader

The highest terminal shoot of a plant.

leaf

A usually flat, green structure of a plant where photosynthesis and transpiration take place and attached to a stem or branch.

leaf axil

The angle between a petiole and the stem.

leaf blight

Any of various diseases which lead to the browning and dropping of a plant’s leaves.

leaf bud

A bud which contains undeveloped leaves.

leaf curl

A disease that causes leaves to roll up.

leaf gap

A break in a stem's vascular tissue above the leaf trace.

leaf litter

The leaves that have fallen from a plant, either through normal seasonal changes or due to disease. Especially in the latter case, leaf litter can harbor pathogens and should be cleaned up promptly, particularly around plants such as roses. In a naturalized, woodland setting, leaf litter can be a normal part of the workings of the garden.

leaf miners

Tiny grubs that tunnel in leaves leaving whitish blotches or trails.

leaf mold

A form of humus composed of decayed leaves, often used to enrich soil.

leaf primordium

A lateral outgrowth from the apical meristem that develops into a leaf.

leaf scar

The mark left on the twig at the point of attachment of a leafstalk when the leaf falls.

leaf spot

Any of various plant diseases that cause well-defined areas of tissue to die creating noticeable spots.

leaf trace

The strand of vascular tissue between the vascular bundle of the stem and the leaf.

leaflet

A single division of a compound leaf.

leathery

Of a smoothly tough texture.

lectotype

A specimen selected from the original material used by the author in naming a taxon, when no holotype was designated or if the holotype is missing. See also: holotype, isotype, nomenclatural type, syntype, topotype, neotype.

lee shore (alt. leeshore)

The shore toward which the prevailing winds are blowing. It is not protected from strong wave action and may have breakers. See also: windward shore.

leeward

The side opposite that from which the wind blows, the sheltered side. See also: windward.

leggy

Refers to a plant growing tall and spindly, usually from inadequate sunlight.

legume

The dry, single-celled fruit of the Leguminosae, formed of a simple pistil, and usually dehiscent by both sutures and often grouped in a long pod, as found in a pea-pod.

leguminous

Pertains to a legume or to the Leguminosae.

lenticular

Lentil-shaped; of the shape of a double-convex lens.

lentiginous

With very tiny dots, as though covered with dust.

lepidote

Beset with small scurfy scales. See also: leprous.

leprous

Scurfy, covered with tiny scales. See also: lepidote.

leptocaul

With a thin primary stem.

leptodermous

Thin-coated; applied to capsules when soft and pliable.

leptosporangiate

Describes a fern with sporangia having walls only one cell thick. See also: eusporangiate.

leptosporangium

A thin-walled sporangium originating from a single epidermal cell.

leucoplast

A colorless plastid in the cytoplasm of interior plant tissues that is potentially capable of developing into a chloroplast.

liana (alt. liane)

Any of various high-climbing woody plants, usually found in the tropics.

lianoid

Vine-like.

lichen

An organism formed by the symbiotic association of an alga and a fungus.

life form

Characteristic structure of a plant or animal.

lifting

Digging up and removing a plant from its surrounding soil.

light frost

A frost where the air has dropped below freezing but the ground has not. Many plants can survive a light frost but cannot survive a hard frost.

light shade

1. Incomplete shade, where some sunlight is still available. 2. An area in shade for only part of the day.

lignin

The chief noncarbohydrate constituent of wood, a polymer that functions as a natural binder and support for the cellulose fibers of woody plants.

lignotuber

A woody swelling on the trunk of a tree or shrub, below or just above the ground, that contains adventitious buds from which new shoots develop if the top of the plant is cut or burnt.

lignum vitae

The very hard, heavy wood of any of several trees of the genus Guaiacum.

ligulate

Furnished with a ligule.

ligule

A strap-shaped corolla, as found in the rayflowers of Compositae. 2. A thin often scarious projection from the summit of the sheath in grasses.

limb

1. A branch of a tree. 2. The expanded portion of any petal, or of a leaf, such as the expanded portion of a gamopetalous corolla above the throat. 3. The upper part of a leaf as distinct from the leaf base.

limbate

Describes a leaf bordered by a part of another color.

limbed

Refers to timber with branches removed.

lime-dots

White salt concretions around a hydathode.

lime-hater

Plant unable to thrive in alkaline.

limnology

The study of fresh water bodies with regard to physical, chemical, geological, meteorological, biological, and ecological conditions. Oceanography encompasses the same specialties for marine salt waters.

line-out

To set out young rooted plants in the outdoor nursery to grow larger or on which to work grafts.

linguiform

Tongue shaped.

Linnaean (alt. Linnean)

Of, or relating to, the Swedish botanist Carolus Linnaeus (1707-1778), or the taxonomic classification system of binomial nomenclature he originated.

lip

Each of the upper and lower divisions of a bilabiate corolla or calyx; the peculiar upper (but by a twist of the pedicel apparently lower) petal in orchids.

lip petal

The lower petals of some irregular flowers, often elaborately showy, as in orchids.

lister

An agricultural implement consisting of a double plow, in which the plowshares force the soil in opposite directions, forming a series of alternate ridges and furrows. The basin lister comes with an attachment that forms low soil dams across each furrow at intervals of 15 to 25 feet (to 6.5 m.), forming basins to hold large amounts of water.

literature retrieval

The process of selecting--manually or automated--appropriate documents within the mass of published literature that are of interest to the user. See also: document retrieval, data retrieval.

lithic context (syn. stratigraphic context)

The rock layers surrounding a fossil that allow the age of the fossil to be determined.

lithophyte

A plant that grows on rocks.

littoral

Of or existing on a shore.

littoral drift

Sediment and detritus moved along the shore by waves and currents. See also: littoral zone.

littoral zone

The shallow water along the shore from zero to the depth where plants no longer root, about 10 feet (3 m.) deep.

liverwort

A nonflowering plant in the botanical class Hepaticae, closely related to the mosses.

loam (syn. loamy soil)

1. A generally fertile and well-drained soil, containing clay, sand, and a significant amount of decomposed organic matter. 2. Any soil.

lobate

Having numerous lobes.

lobe

Any segment of an organ, especially if rounded.

lobedleaf

A leaf whose margin is shallowly divided.

lobulate

With irregular, rounded lobes.

location survey

A less expensive land survey done to only prove that a specific building or right of way is situated on a plot of land, rather than the more detailed metes and bounds survey which gives all border limitations and positions.

lociation

A variation of a climax association, differing from the normal in the kinds of subdominants. See also: faciation.

loculicidal

Longitudinally dehiscent between the partitions of the locule, as in Liliaceae. See also: septicidal.

locus (pl. loci)

The position in a chromosome of a particular gene or allele.

lodicule

One of a pair of tiny scales at the base of a grass floret, believed to a be reduced perianth segments.

loess

A deposit of relatively consistent fine soil, mostly silt, usually carried by wind.

log lifter

A tool designed to easily roll a log, a cant hook, or pike.

loment

On legumes, a pod which narrows between the seeds, drying and splitting apart at maturity into one-seeded segments.

lomentum

A pod constricted between the seeds.

long-day

Of, relating to, or being a plant which flowers only after being exposed to daylight for periods longer than a particular length, usually in the late spring or early summer.

long-lived

Describes a plant where the individuals subsist for a number of years.

longitudinal

Lengthwise.

loppers (alt. lopping shears)

Long-handled pruning shears for cutting larger branches; may be rachet tools, with telescoping handles or specialized long reach type.

lorate

Strap-shaped.

lotic

Of, relating to, or living in actively moving water. See also: lentic.

luculicidal

Dehiscent into the cavity at a cell through the dorsal suture.

lumen (pl. lumina)

The central cavity of an organ or cell.

lunate (alt. lunulate)

Of the shape of a half-moon or crescent.

lustrotts

Glossy.

lutein (syn. xanthophyll)

A yellow carotenoid pigment, usually found with chlorophyll in plants. Also called xanthophyll.

lyrate

Pinnatifid with a large and rounded terminal lobe and with the lower lobes small.

machete

A large powerful knife used to clear brush, e.g., trails through jungle areas.

macrophytes

All visible plants in any habitat, not microscopic bacteria or algae.

macrosporangium

The receptacle in which macrospores are developed.

macrospore

The larger kind of spore in Selaginellaceae, etc.

maculate

Blotched with broad, irregular patches of color.

main shoot

A basal cane or a strong lateral cane.

male cone

The conical, pollen-bearing male element of a conifer.

mallee

A growth form in which several stems arise from a lignotuber.

malpighiaceous hairs

Hairs which are straight and oppressed but attached by the middle.

mamillate (syn. mammillar)

Convex with a short projection in the center.

mammillate (alt. mammillated)

Shaped like a nipple.

manila coin envelopes

Small easily labeled containers for otherwise easily lost parts of plant specimens such as seeds, individual flowers, leaves, etc.

manure

Animal dung used as a fertilizer.

marcescent

Withering but persistent.

marginal rays

Fully developed ray florets which establish and determine the maximum diameter of a flower, as distinguished from the immature central rays (used in describing dahlias.)

marginate

With a border of a different color.

maritime

Describes climate mainly influenced by the sea, generally with mild winters, cool summers, and frequent rain.

marl

A mixture of clay and the carbonates of calcium and magnesium, from precipitation in acidic waters, and from dissolved shells and limestone.

massula (pl. massulae)

Structures associated with megaspores or enclosing and trapping microspores to increase the likelihood of fertilization.

matted

Formed into a mat.

mattock

A waist-high tool with a metal head consisting of a horizontal blade with one end twisted as a dull axe and the other end flat or pointed. It is used for breaking hard soil, digging roots, and other heavy work.

maze (syn. maze garden)

A confusing intricate network of passages, particularly one created with tall, dense hedges forming the walls and separating the pathways.

meadow

Typically, a level grassland or field within a larger ecosystem, such as a forest. Often, the grass grown on its natural, low-lying, moist areas is used for forage or fodder or cut for hay.

mealy

Farinose.

mealybug

Any of the scale insect belonging to the family Pseudococcidae that have a white powdery covering and are destructive plant pests, particularly toward fruit trees.

median

Refers to the central crosswise area of a leaf, as 'median width' would be the broadest width at midpoint.

median leaf-cells

Cells from the middle of the leaf.

medicinal herb

Any herb which is used as a curative or preventative.

medifixed

Attached by or at the middle.

medulla

1. The central tissue of a structure, generally referring to the pith. 2. The inner part of the thallus of a lichen.

medullary

Made up of pith, spongy.

megasporangium (pl. megasporangia)

The female sporangium containing the megaspores.

megasporophyll

The leaf bearing the megasporangia.

meiosis

Cell division; the nuclear division that halves the chromosome number.

meiotanglum

The sporangium or gametangium in which meiosis occurs.

mellitophily

Pollination by bees.

membranaceous (syn. membranous)

Like a membrane; thin, rather soft, and more or less translucent.

membranous (alt. membraneous, alt. membranaceous)

Thin in texture, soft and pliable.

meniscoidal

Thin and concavo-convex, like the crystal of a watch.

mentum

A chin-like extension on a flower, particularly in Orchidaceae.

mericarp

One of the achene-like carpels of Umbelliferae.

meristem cloning (n. mericlone)

Artificial propagation of a plant using cells taken from the meristem of a parent plant and yielding genetically identical offspring.

Merrill cases

Cardboard containers purchased flat for easy transport, then opened in the field when needed to hold plant specimens.

mesic

Of, or adapted to, a temperate, moderately moist habitat; neither xeric nor hydric.

mesocarp

The fleshy, middle portion of the wall of a succulent fruit between the skin and the stony layer.

mesophyll

The middle and photosynthetic tissue of a leaf.

mesophyte

Dryland plants, xerophytes, have adaptations to survive for months with no water; water plants, hydrophytes, live in water; mesophytes are all other plants--which need small amounts of water on a regular basis.

mesosperm

The middle layer of the coat of a seed.

metaxylem

The primary xylem formed after the protoxyle.

metes and bounds

A surveyor's term meaning the legal circumscribing lines setting the outer limits of a tract of land.

microclimate

Climate specific to a small area; may var. significantly from that of surrounding areas.

microconidia

Bacilliform cells produced in pycnidia.

microenvironment

The environment of a very small area.

microevolution

Evolution as a result of very small genetic variations, which may cause the formation of a new subspecies.

microfossil

A microscopic fossil, e.g., that of a pollen grain.

microgametophyte

The male gametophyte, formed by vegetative growth of the microspore of a heterosporous plant.

microhabitat

A very small habitat, such as a rock crevice or a clump of grass.

micronutrient

An organic compound, such as a vitamin, essential in minute amounts to the growth and health of a living organism.

microphyll

A very small leaf.

micropropagation

Propagation of plants through tissue cultures.

micropyle (adj. micropylar)

1. A minute opening on the ovule through which the pollen tube usually enters. 2. The point upon the seed at which was the orifice of the ovule.

microsporangium (pl. microsporangia)

The male sporangium in which microspores are developed.

microsporophyll

The leaf bearing the microsporangi.

midrib

The central or main rib of a leaf.

midvein

The principal vein in the blade of leaf, pinnule, or segment.

mildew

A fungus that leaves a thin white coating on the surface where it grows.

mimosiform (alt. mimosoid)

With round or conical flower heads having inconspicuous sepals and petals but conspicuous stamens, as found in the genus Mimosa.

ming

A dwarfed evergreen conifer grown as bonsai.

minimum viable population

The isolated population of least numbers which has a good chance of surviving despite the foreseeable effects of demographic, environmental, and genetic events and natural catastrophes.

misapplied

Refers to the usage of a taxon name for an incorrect plant; such names are homonyms and also synonyms of the plants to which they truly describe.

mitochondrion (pl. mitochondria, syn. chondriosome)

Cytoplasmic structure containing enzymes used in converting food to energy.

mitosis

Cell division in which the number of chromosomes in the daughter cells is the same as that of the parent cell. See also: meiosis.

mitriform

Shaped like a mitre or cap.

moat

A ditch filled with water and usually acting as a barrier.

moniliform

Resembling a string of beads; cylindrical with contractions at intervals.

mono-

A prefix meaning one.

monocarpellary

Refers to fruit with one female organ.

monocarpic

Describes a plant that dies after flowering just once.

monocephallic (alt. monocephalous)

Bearing a single flower head.

monocephallous

Having a single flower head.

monochasial cyme

Like a dichasial cyme, but with branches on only one side.

monochasium (pl. monochasia, adj. monochasial)

A cyme with a single flower on each axis of the inflorescence.

monochlamydeous

Describes a flower which has a single whorl of perianth parts.

monoclinous (alt. monoclinus)

Having pistils and stamens in the same flower.

monocolpate

Refers to pollen grains with a single furrow.

monocotyledon (alt. monocot, adj. monocotyledonous)

A plant with one cotyledon or seed leaf.

monoculture

The agricultural practice of planting a field or other land mass with a single crop, all of the same age, like wheat or pine trees. Single crop planting often leads to increased infestation by disease or insects.

monoecious (alt. monoicous)

Having stamens and pistils in separate flowers on the same plant.

monoembryonic

Refers to seeds or ovules with a single germ cell or embryo.

monogeneric

Refers to a family or taxon of higher rank made up of a single genus.

monolete

Describes spores having a single, unbranched scar.

monomial

The single word designation such as genus Iris, or family Iridaceae. See also: binomial.

monopetalous

In the strictest sense, refers to a flower with a single petal; however, it is often used to refer to gamopetalous flowers in which several petals are united to form a tube.

monophyletic

Descended from a single ancestral line. See also: polyphyletic.

monoploid

Having a single set of chromosomes.

monopodium (pl. monopodia, adj. monopodial)

The main axis of a stem or rhizome maintaining a single direction of growth and giving off lateral branches or stems. See also: sympodium.

monospecific

Refers to a genus which has a single species.

monotypic

A taxonomic division that has only one subdivision, as a family containing only one genus, or a genus with a single species.

montane

Of, growing in, or inhabiting mountain areas.

morphocline

A graded series of character states of a homologous character.

morphology

The study of the form and structure of an organism.

moss

A small nonflowering plant of the class Musci.

mother bulb

A mature bulb which has produced small offset bulbs.

mother plant

1. A mature plant from which cuttings are taken. 2. The female ancestor of a hybrid.

mother-cell

The cell that gives rise to a particular structure or particular reproductive units.

motile

Actively moving or capable of moving spontaneously.

mottled

With variegated coloring.

mound layering

A method of propagation whereby a branch or stem is scored and then brought into contact with the soil to spur rooting.

moxa

A Chinese herbal process of burning dried herbs on or above the skin to stimulate an acupuncture point or serve as a counterirritant.

mucilage (adj. mucilaginous)

A viscous, slimy material exuded by certain plants.

mucous

Slimy; viscous.

mucro

A short and small abrupt tip.

mucronate

Refers to a leaf or other organ ending suddenly with a stiff spine as a continuation of the midrib; tipped with a mucro.

mucronulate

Diminutive of a mucronate, with a small spine.

mud flats

The bare level bottoms of bodies of water exposed by a drop in the water level. A mud bar may be exposed in a constant water level by a buildup of sediments.

mud logger (mud logging)

A person who works with geologists, lubricating the cutters of cores, and analyzing the resulting rock fragments for stratigraphy, keeping a record or log of the results.

muddled center

A flower center with petals that are disorganized, not forming a pattern. A term applied to Old Garden Roses.

mulch

An organic or inorganic soil covering, used to maintain soil temperature and moisture and to discourage the growth of weeds.

multi-

A prefix meaning many.

multicellular

Formed of two or more cells.

multicipital

Many-headed.

multifid

Cleft into many lobes or segments.

multigeneric

Refers to hybrids with more than two generations in their ancestry, e.g., x Potinara (Brassavola x Cattleya x Laelia x Sophronitis).

multiline

A term used by nurseries to indicate that a horticultural variety derives from several closely related lines.

multiplanar

Describes divided leaves, with the lobes held in several to many planes.

multiple fruit

One in which the carpels of several flowers join in a single fruit, like a fig, Ficus. This differs from an aggregate fruit which derives from the multiple carpels of a single flower, e.g., a raspberry, Rubus.

multiseptate

Bearing more than two septae.

muricate

With a rough surface composed of many short, hard points.

muriculate

Very finely muricate.

muriform

Divided into many chambers.

muscariform

Shaped like a broom.

mutant

1. An individual produced with sudden and marked differences from the parent, and with a new genetic pattern. 2. A sport.

muticous

Not pointed.

mutualism

A type of symbiosis in which both members depend on each other for their nutrients or other services.

mycelium (pl. mycelia)

The mass of interwoven filamentous hyphae that forms especially the vegetative portion of the thallus of a fungus.

mycology

The study of mushrooms and other fungi.

mycorrhizal

A term describing plants which have a symbiotic relationship with the mycelium of a certain fungus.

myrmecophilous

Strictly, ant-loving; refers to plants which have symbiotic relationships with ants.

myrmecophyte

A plant in symbiosis with ants.

named cultivar

A cultivar that has been given a recognized horticultural name.

napiform root

A taproot which is broader than it is long, like a turnip.

narcotic

A drug used to relieve pain and induce sleep.

native plant

A plant occurring naturally in an area and not introduced by man; indigenous.

natural layering

The spontaneous rooting of stems when they make contact with the soil.

naturalize (alt. naturalise)

1. To cause a plant to become established and grow undisturbed as if native. 2. The establishment of exotic species in the wild that can reproduce without human intervention.

Boat-shaped.

nec

In nomenclature, this is placed between the names of two authors, indicating that neither named the taxon in a valid manner.

neck

The lowest part of the capsule just above the point where it joins the seta.

necrosis

The localized death of living tissue usually caused by a pathogen.

nectariferous

Producing nectar.

nectarivore

An animal, including insects and bats, that eats nectar.

nectary

Any place or organ where nectar is secreted.

needle

The very long and narrow leaf of pines and related trees.

needle-like

Very long, narrow, and pointed at the tip.

nematode

Any of several unsegmented, elongated cylindrical worms of the phylum Nematoda. They may be parasitic in animals or plants, or free-living in soil or water. As parasites, they can cause damage to and even kill plants. Others can be benficial.

neotenic

Refers to retaining juvenile characteristics throughout the life span.

neoteny

The process of fulfilling a function in an imperfect or young state.

neotype

A specimen selected to serve as the nomenclatural type when the material used to base the name of the taxon is missing. See also: holotype, lectotype, nomenclatural type, syntype, topotype, isotype.

nervine

An herbal medicine with a soothing and mildly sedative action.

nest-fronds

Specialized, shield-shaped, basal fronds in some ferns which accumulate leaf litter forming a nest-like covering.

net-veined

With a network of veins.

neuter (syn. neutral)

Without stamens or pistils.

neutral soil

Soil having a pH of 7 and therefore neither acidic nor alkaline.

neve

Granular compacted snow at the head of a glacier, or similar snow elsewhere. See also: firn.

niche

1. Ecological niche--the role of a plant or animal in the environment, its relationship to all the living and nonliving things around it, e.g., a bat is the nighttime hunter of airborne insects. 2. Habitat niche--the specific part or smallest segment of a habitat occupied by an organism, e.g., a pillbug lives under moist rocks or detritus. See also: biotope.

nigrescent

Turning black.

nitrification

The oxidation, as by bacteria, of ammonium to nitrites and the further oxidation of nitrites to nitrates.

nitrogen carrier

A material such as a commercial fertilizer that contains the essential mineral nitrogen.

nitrogen fixation

The conversion of atmospheric nitrogen into an organic form usable by plants and other organisms. This can be through the agency of soil microorganisms, particularly rhizobia living in nodules on the roots of legumes, or by industrial methods.

nocturnal

Active only at night; flowering only at night.

nodose

Knotty or knobby.

nomen (pl. nomina)

Literally, "name", particularly a scientific name assigned according to the Codes of Nomenclature.

nomen ambigua (abr. nom. ambig., alt. nomina ambigua)

A name that has long referred to different taxa and should be abandoned.

nomen confusum (abr. nom. confus., alt. nomina confusa)

A name based on a type, the herbarium specimens later proving to be two or more taxa.

nomen conservandum (abr. nom. cons., alt. nomina conseranda)

A taxon name that has been formally accepted under the International Code for botanical nomenclature as the correct name contrary to the usual principles of botanical nomenclature.

nomen illegitimum (abr. nom. illegit.)

A name that was validly published, but contravenes the International Code for botanical nomenclature; A name which was superfluous or had already been applied to another plant.

nomen novum (abr. nom. nov.)

A name proposed to replace a name which has been rejected.

nomen nudum (abr. nom. nud., alt. nomina nuda)

Literally, "a naked name". Used in nomenclature to refer to the fact that the name was published without a description or diagnosis and is therefore not acceptable under the International Code for botanical Nomenclature.

nomen rejiciendum (abr. nom. rejic., alt. nomina rejicienda)

Literally, "a name to be rejected". Used in nomenclature when a decision has been made to conserve an older name and the newer one is rejected. See also: nomen conservandum.

nomenclatural synonym

Any one of two or more different names based on the same plant specimen.

nomenclature

A system or set of terms or symbols; the system of providing taxonomic names for organisms.

non

In nomenclature, it means 'not' as in "Artemisia lanata Willd. non Lam."---when Willdenow in 1823 gave a new plant the same name that Lamarmarck had used in 1783 for a different plant.

nongovernmental organization (abr. NGO)

A nonprofit group or association organized outside of institutionalized political structures to gain particular social objectives such as environmental protection.

nonvascular

Refers to organisms with no tissues or vessels to carry water, minerals, etc., such as mosses, fungi, algae, lichens, etc.

nostoc

A blue-green alga with filaments formed of chains of cells.

notch

A v-shaped indentation.

nothomorph

A term used in taxonomy to designate different hybrid forms derived from the same parent species, ranking essentially as a variety.

novirame

A flowering--later fruiting--shoot arising from a primocane.

noxious weeds

Plants which may cause harm to collectors, such as poison ivy, Toxicodendron radicans; or invasive exotics or parasites and their host plants which may harm the ecosystem or agriculture of an area. See also: quarantine.

nucellus (adj. nucellar)

The central body of the ovule that encloses the female gametophyte; equivalent to the megasporangium.

nucleolus

A special body in the nucleus.

nucleus (pl. nuclei)

1. The germ cell of the ovule, which by fertilization becomes the seed; the kernel of a seed. 2. The part of the protoplasm that contains the chromosomes.

nullipores

Calcareous red seaweed.

nurse grass

A fast-growing temporary grass included in most grass seed mixtures to give rapid coverage and protect permanent grasses from soil erosion, sunscald, etc.

nurse tree

A fast-growing tree planted with, or left in place near, a slow-growing, permanent tree in order to provide shade and wind protection for the permanent tree until it has reached useful size.

nut

A dry, hard indehiscent 1-celled and 1-seeded fruit, though usually resulting from a compound ovary.

nutant

Nodding, usually referring to the entire inflorescence rather than a single flower; cernuous.

nutlet

One of several small, nut-like parts of a compound fruit; a diminutive nut.

o.c.

On center; refers to the spacing on landscape plans of materials to be planted.

ob-

A prefix meaning inverted, e.g., obcordate describes a heart-shaped leaf attached at the point rather than at the cleft.

obcompressed

Compressed dorso-ventrally instead of laterally.

obconically

Inversely conical, having the attachment at the apex.

obcordate

Inverted and heart-shaped; e.g., a heart-shaped leaf with the pointed end toward the stem.

obcuneate

Like cuneate, but with the point of attachment at the broad end.

obelisk

An upright four-sided usually monolithic pillar that gradually tapers as it rises and terminates in a pyramid, often inscribed with words or designs.

obhastate

Like hastate, but with the triangular lobes at the tip.

oblanceolate

Lanceolate with the broadest part toward the apex.

oblate

Shaped like a sphere which is depressed at the poles.

obligate

Incapable of surviving without a host, as occurs with certain parasites. See also: facultative.

oblique

Unequal-sided or slanting.

obloid

Having an oblong shape but with the cross section circular and the ends rounded.

oblong

Longer than broad and with nearly parallel sides.

obovate

Inverted ovate; egg-shaped, with the broadest part above, or away from the stem.

obovoid

Having the form of an inverted egg.

obpyramidal

Shallowly triangular with the attachment at the point rather than the middle of the flat side.

obpyriform

Inversely pear-shaped, with the attachment at the narrow end; turbinate.

obscure

Hidden.

obsolescent

Becoming rudimentary; refers to an organ no longer functional and reduced to vestigial remains.

obsolete

Not evident; rudimentary.

obtuse

Blunt or rounded at the end.

ocellated

Having spots.

ochrea

The sheath around the base of the seta, terminating the vaginula.

ochroleucous

Yellowish-white.

ocrea (alt. ochrea)

A legging-shaped or tubular stipule.

octoploid

Having eight sets of chromosomes.

odd pinnate

A pinnate leaf with a terminal leaflet, hence having an odd number of leaflets.

odoriferous

Producing an odor, often fragrant.

officinal

Of the shops; a plant used in medicine or the arts.

offset

A short sideshoot arising from the base of a plant; also a small bulb arising from the base of another bulb.

offshore wind

Blowing from the land across the water, usually warmer than an onshore wind, and with lower waves.

Old Garden Rose (abr. OGR, syn. Old English Rose)

A hybrid rose which has been in cultivation since before 1867.

oleaginous

Refers to fleshy, oily tissue.

oligo-

A prefix denoting few, as oligopetalous means with few petals.

once-compound

A compound leaf with a single set of undivided leaflets.

onshore wind

Blowing from the water to the shore, building large waves as it uses its full fetch. This is usually cooler than an offshore wind.

ontogeny

The course of development of a single organism.

oocyte

A cell from which an egg develops.

oogamy

Conjugation between sperms and egg.

oogonium

The organ producing the egg or eggs.

ooshere

The egg cell or ovum found in the base of the archegonium.

oospore

The fertilized nucleus or germ-cell of the archegonium in cryptogams, from which the new plant is directly developed.

opaque

Dull; neither shining nor translucent.

open pollination

Pollination by natural mechanisms such as insects, wind, etc., as opposed to selective pollination by a plant breeder.

operculate

Furnished with a lid.

operculum

A lid; the upper portion of a circumscissile capsule, which on detachment permits the spores to escape.

opposite

Describes leaves arranged along a twig or shoot in pairs, opposite each other at a single point along an axis.

orangery

A many-windowed building used to house potted orange trees during winter.

orbicular

Circular.

orbiculate

Circular in outline.

orchard

A planting of fruit or nut trees.

order (alt. ordo)

A category of taxonomic classification ranking above the family and below the class.

organelle

A membrane-bound body analogous to an organ and found in the cytoplasm of the cell that performs specific cellular functions.

organic

Derived naturally, from living or once-living matter.

ornamental

A plant that is grown for visual display.

ornamental tree

Generally, a small tree as opposed to a tall, or shade, tree. Often they are flowering trees used as understory plantings, or massed in the open for color and texture.

orthodox seed

Seed that can be dried to moisture levels between 4 and 6 percent and stored without spoiling.

orthotropic

Tending to grow or form along a vertical axis.

orthotropous

Describes an ovule or seed that is erect, with the orifice or micropyle at the apex.

osmosis (adj. osmotic)

The diffusion of liquid through a semipermeable membrane (such as a cell wall) until there is an equal concentration on both sides of the membrane. The process by which water is taken up through the roots of a plant and transported throughout the structure.

osseous

Bony and brittle.

ostiole (adj. ostiolar)

A small opening or pore.

outbreeding

The interbreeding of distantly related or unrelated individuals.

outcross

1. A cross between relatively unrelated individuals. 2. The offspring of an outcross.

oval

Egg-shaped. See also: ovate, oviform.

ovary

The part of the pistil that contains the ovules.

ovate

Egg-shaped, with the broader end at the base. See also: oval, oviform.

overhead watering

Watering from above, usually with a sprinkler or a hose with a sprinkler attachment.

overstocked

1. Refers to a stand that contains more trees or other materials than the site can support, causing tall, weak growth and the tendency to blow down. 2. Refers to a range which has more wildlife or domestic stock than the area can support. See also: fully stocked, understocked, carrying capacity.

overtopping

When one branch of a dichotomy grows more than the other.

overwinter

1. To survive the winter. 2. To keep alive through winter, e.g., bringing a nonhardy plant indoors, wrapping roses or mulching pansies.

ovid

Broadly elliptical.

oviform

Shaped like an egg. See also: oval, ovate.

oviparous

Producing female reproductive cells.

ovoid

A solid with an oval outline.

ovule

The body which, after fertilization, becomes the seed.

ovuliferous

Bearing ovules.

pachycarpous

Describes a seed having a thick outer layer or pericarp, e.g., the skin on a cherry. The skin (epicarp, ectocarp, or exocarp), flesh (mesocarp or sarcocarp), and stony outer layer of the seed (endocarp) form a pachycarpous covering of the seed proper.

pachycaul

With thick or massive primary construction.

pachydermous

Thick-skinned; applied to the walls of capsules or to cells when firm and resisting.

pack ice (alt. ice pack)

A large area of ice driven closely together.

pagoda

A tower of Far Eastern design usually with roofs curving upward at the division of each of several stories and erected as a temple; a similarly styled garden structure.

paired

Refers to flowers or leaflets in opposite pairs, but bi-, tri-, and multijugate further describe leaflets with two, three, or many such pairs or parts.

palate

A rounded projection of the lower lip of a personate corolla, closing the throat.

palea (syn. palet)

The upper bract which, with the lemma, encloses the flower in grasses.

paleaceous

Clothed with chaff.

Paleobotany (syn. archeobotany)

The study of plant fossils.

paleophytological

Relates to the study of fossil plants.

palisade

Refers to the layer of columnar photosynthetic cells in the leaf.

palm

Any of various plants of the family Palmae, mostly tropical or subtropical monocotyledonous trees, shrubs, or vines, usually having a simple stem and a terminal crown of large pinnate or fan-shaped leaves.

palmate (adj. palmately)

Describes a leaf that is radially lobed or divided.

palmate-veined

With the principal veins arising from the end of the leafstalk and radiating toward the edge of the leaf.

palmately compound

Having veins or leaflets arranged like the fingers on a hand.

palmatifid

Describes a leaf which is deeply, but not completely, divided into several lobes.

palmatisect

Intermediate between palmate and palmatifid.

palustrine

Refers to areas that are not part of a major lake, but are filled with partially decomposed plant materials to considerable depth in wetlands such as bogs, swamps, and marshes. See also: peat.

palustrine wetlands

Those not a part of a main lake, therefore not subject to intensive wave or current effects.

palynology

The scientific study of pollen and spores.

pampas

An extensive, generally grass-covered plain of temperate South America, located east of the Andes and mostly in Argentina.

pan

A layer of different soil below the surface, often impervious, which would be called hard pan.

panacea

A remedy for all ills or difficulties; cure-all.

pandurate (syn. panduriform)

Fiddle-shaped; with a rounded base, narrow waist, rounded upper part and long neck.

panicle

A loose, irregularly compound inflorescence with pedicellate flowers.

panicled (alt. paniculate)

Borne in a panicle; resembling a panicle.

pannose

Like felt in texture, densely covered with hairs.

pantoporate

Describes a pollen grain having rounded apertures all over the surface.

pantropical

Spanning tropical regions around the world.

papilionaceous

Describes a corolla having a standard, wings, and keel, as in the peculiar corolla of many Leguminosae.

papilla (pl. papillae)

1. A minute, nipple-shaped projection. 2. Small bumps appearing on either the upper cortex or lower surface of various lichens.

papillaer

Minute rounded or acute protuberances.

papillate

Bearing papillae.

papillose (syn. scabrose)

Bearing minute nipple-shaped projections; rough with papillae.

pappus

The modified calyx-limb in Compositae, forming a crown of various character at the summit of the achene.

papule

A relatively large pustule, papilla, or pimple.

papyraceous

Paper-like.

paraclade

An inflorescence on a lateral axis which repeats the symmetry of the primary axis.

paradichlorobenzene

A white crystalline compound used in moth balls and moth crystals and often placed with herbarium specimens to prevent destruction by moth larvae. Large quantities in a closed container may be used to kill insects needed as part of sample.

parallel-ribbed (syn. parallel-veined, syn. parallel-nerved, syn. penniparallel)

With the veins running more or less parallel toward the tip of the leaf.

paraphyllia

Minute leaf-like or much-branched organs among the leaves.

paraphysis (pl. paraphyses)

1. Jointed hyaline hairs growing among the reproductive organs. 2. The thread-like hyphae between the asci.

parasite

A plant deriving its nutrition from another organism; the dependent member of parasitism.

parasitization

The process whereby one organism lives on or with another as a parasite.

parenchyma

Soft tissue of cells with unthickened walls.

parenchymatous

Cells with broad ends abutting on each other, not dovetailing into each other.

parietal

Borne on or pertaining to the wall or inner surface of a capsule.

paripinnate

Having an even number of pinnae. See also: imparipinnate.

parkland

Land in which clumps of trees are scattered throughout a grassland. See also: parks.

parks

Areas set aside by government and kept in their natural states for the purpose of conserving unique areas for preserving game, walking, riding, or recreation.

paroicous

Having its male and female organs in the same cluster, but not mixed, the antheridia being in the axils of the perichaetial bracts below the archegonia.

parterre

A formal garden of intricately designed, geometrically shaped beds of flowers, herbs, and low shrubs separated by pathways and/or lawns.

parthenocarpic

Refers to the fruiting of plants which have not been pollinated or otherwise fertilized.

parthenogenetic

Developing without fertilization.

partial

Of secondary rank.

partite

Parted.

partitioned

The pith divided crosswise by woody plates, usually near the leaf scars.

pasture

A grassland which is used as graze for domestic animals.

patellate (alt. patelliform)

Round and thick, with one side concave and the other following the same curve by being convex, like a thick contact lens.

patent (alt. patulous)

Spreading, as do the branches of a tree; particularly at an angle of 26-45 degrees.

pathogen

A disease-causing agent, especially a bacterium, fungi, or other microorganism.

pathological

Diseased.

patina

The changed color or texture of a surface due to weathering or aging.

patulous

More widely spreading than patent.

pea-like

Refers to a flower with a top banner or standard, similar to legume blossoms; papilionaceous.

peat bog

An area with a wet, spongy, acidic substrate, consisting mainly of accumulated layers of sphagnum moss and upon which other plants, and even trees, can grow.

peat moss

Partially decomposed sphagnum moss, often added to soil to increase moisture retention.

peavey (alt. peavy)

A tool similar to a cant hook, but with the tip outfitted with an iron spike rather than a ring.

pectin (adj. pectic)

Any of various water-soluble substances that bind adjacent cell walls in plant tissues and yield a gel which is the basis of fruit jellies.

pedicel

1. A tiny stalk; the support of a single flower. 2. The stalk of the sporangia. See also: seta.

pedicelled (alt. pedicillate)

Borne on a pedicel.

peduncle

A primary flower stalk, supporting either a cluster or a solitary flower.

peduncled (alt. pedunculate, alt. peduncular)

Borne upon a peduncle.

pegging

Securing the ends of canes to the ground so that the plant grows horizontally.

pellucid

Clear, transparent.

peloria (adj. peloric)

Unusual regularity or symmetry in the form of a flower that is normally irregular.

peltate

1. Describes a leaf attached to the petiole from near the center of the lower surface, and not at the margin. 2. Shield-shaped.

pendant

Hanging downward.

pendular

Having the movement of a pendulum.

pendulous

More or less hanging or declined. Pendulous ovule: one that hangs from the side of the cell.

penicillate

Tufted with small hairs.

penniribbed (syn. penninerved, syn. penniveined)

Having conspicuous lateral veins which are divergent from the midrib and approximately parallel to one another.

pentamerous

Describes a flower which has five parts in each floral whorl.

pentangular

With five angles, as the cross-section of a stem.

pentaploid

Having five sets of chromosomes.

pepo

A fruit, such as that of a melon or squash, having a firm rind, fleshy pulp, many flattened seeds, and a single locule.

perched water table

The water table of a smaller body of groundwater body situated above the general groundwater table.

percurrent

Describes a costa that reaches to the apex of the leaf, but not beyond.

perennate (n. perennation)

To live for more than one growing season, but usually with reduced growth or dormancy between growing seasons.

perennial

A plant whose life cycle lasts for three or more seasons; Lasting year after year.

perfect

Describes a flower having both pistil and stamens.

perfoliate

Describes a leaf having the stem apparently passing through it.

perforate

Pierced with holes.

pergola

An open structure usually consisting of parallel columns supporting an open roof of cross rafters on which climbing plants are trained to grow; an arbor.

perianth

The floral envelope, consisting of the calyx and corolla (when present), whatever their form.

pericarp (syn. fruit wall)

The wall of the matured ovary.

perichaetium (pl. perichaetia, adj. perichaetial)

A whorl of bracts at the base of reproductive organs. In mosses, those surrounding the archegonia and base of seta.

pericycle

The tissue of the stele lying just inside the endodermis.

periderm

An outer, cortical protective layer of many roots and stems that typically consists of phellem, phellogen, and phelloderm.

perigone

The perianth, especially when made up of tepals, or in reference to anything surrounding the reproductive structure.

perigonium (pl. perigonia, adj. perigonial, syn. perigone)

1. The perianth. 2. In mosses, those bracts surrounding the antheridia.

perigynium

The inflated sac which encloses the ovary in Carex.

perigynous

Adnate to the perianth, and therefore around the ovary and not at its base.

periodicity

Repetition of events at fairly regular intervals.

peripheral

On or near the margin.

periphyton

The assemblage of organisms submerged in water, attached to surfaces above the bottom of the body of water. See also: benthos, plankton.

perisperm

The nutritive tissue in an angiosperm seed that surrounds the embryo, formed from the nucellus. See also: endosperm.

peristome

The fringe surrounding the mouth of the capsule upon removing the lid.

perithecium (pl. perithecia)

A small flask-shaped structure, containing asci.

perlite

A lightweight aggregate made from a volcanic glass that has been expanded by heat to form white, very lightweight kernels useful in opening cavities in soil to allow water and air to reach the roots; often used in potting soil.

permaculture

The maintaining of a permanent horticulture or agriculture by relying on renewable resources and compatibility with the local ecosystem.

permafrost

Frozen ground in arctic and subarctic areas which does not thaw in summer.

persistent

Lasting beyond maturity without being shed, as some leaves remaining through winter, etc.

personate

Describes a corolla which is bilabiate, and the throat closed by a prominent palate.

perula (pl. perulae, alt. perule)

1. One of the scales of a leaf bud. 2. A pouchlike portion of the perianth in certain orchids.

perulate

Describes leaf buds which are covered with scales.

petal

A division of the corolla; one of a circle of modified leaves immediately outside the reproductive organs, usually brightly colored.

petaliferous

Bearing petals.

petaline

Of or resembling petals.

petaloid

1. Colored and resembling a petal. 2. Additonal floral parts on ray florets having the form and appearance of smaller petals, e.g., in the Collarette dahlias.

petiolate

Having a petiole.

petiole (syn. leafstalk)

The stalk of a leaf that attaches to the stem.

petiolulate

Having a petiolule.

petiolule

The stalk of a leaflet.

phanerogam

A general name for flowering plants.

phaneropore

Superficial stoma.

phellem

A layer of usually suberized cells produced outwardly by a phellogen.

phelloderm

A layer of parenchyma produced inwardly by a phellogen.

phellogen (syn. cork cambium)

A secondary meristem that produces phellem and phelloderm in the periderm of a trunk or stem.

phenetic classification

The grouping of taxa by apparent similarities rather than evolutionary genetics.

phenology (adj. phenological)

The science of the relations between climate and periodic biological phenomena, e.g., the fruiting of plants or the color change of leaves.

phenotype

The morphological, physiological, behavioral, and other outwardly recognizable adaptations of an organism that develop through the interaction of genes and environment. See also: genotype.

phenotypic

Refers to a plant's adaption to surrounding conditions, which are neither stable nor capable of being inherited (genotypic). Such visible changes occur especially where plants are grown in a wide variety of conditions, but will not carry over to different conditions, e.g., red leaves may occur in hot dry areas, but turn green when grown in normal conditions.

pheromones

Chemical substances produced by animals that attract and stimulate sexual partners of the same species.

photic zone

The upper layers of bodies of water into which sunlight penetrates sufficiently to influence the growth of plants and animals. See also: aphotic zone.

photohetrotroph

Describes an organism using light as a source of energy and organic materials as a carbon source.

photomania (adj. photomanic)

The response of an organism of seeking or growing toward light. See also: phototropism.

photomorphogenesis

The formation and differentiation of tissues and organs controlled by radiant energy, particularly light.

photoperiod

The duration of an organism's daily exposure to light.

photoperiodic

Describes growth affected by exposure to light.

photophobia (adj. photophobic)

The dislike of light, as displayed by bugs that hide under rocks or bats which sleep all day and fly at night. See also: photomania, aphototropism.

photophosphorylation

The synthesis of ATP from ADP and phosphate that occurs in a plant using radiant energy absorbed during photosynthesis.

photosynthesis

The manufacturing of sugar through the action of sunlight.

phototaxis

The movement of a body toward or away from a light source.

phototropism (adj. phototropic)

Growth or movement toward or away from a light source.

phreatophyte

A plant that can endure inundations of salt, such as cattails, Typha, which can live in estuaries, sieving out the saline molecules of seawater at a cellular level.

phyllary

One of the bracts under the flower head of a plant, especially in Compositae.

phylloclade (alt. phylloclad, syn. cladode, adj. phyllocladous)

A flattened, photosynthetic stem that performs the functions of a leaf, as occurs on some cacti. See also: cladophyll.

phyllocladia

Tiny life-like structures of some lichens.

phyllode

A flat expanded petiole that replaces the blade of a foliage leaf and fulfills the same functions. See also: cladophyll.

phyllodium (pl. phyllodia)

A somewhat dilated petiole having the form of and serving as a leaf blade.

phyllopodium

An outgrowth of the rhizome to which the frond is joined in some ferns.

phyllotaxy (alt. phyllotaxis)

The manner of leaf arrangement on a stem.

phylogenetic classification

The grouping of taxa by genealogical descent; evolution.

phylogeny (adj. phylogenetic)

The evolutionary development of a taxonomic group.

phylum

A major taxonomic grouping in the animal kigdom, ranking just below kingdom and above class. In the plant kingdom, it is usually replaced by the division.

physiographic climax

A pinnacle habitat controlled by the topography of the area; e.g., a forest growing on a north slope and a grassland on the south slope of the same ridge. See also: edaphic climax, biotic climax.

phytochemistry (adj. phytochemical)

The chemistry of plants, plant processes, and plant products.

phytochrome clocks

The coloring processes of plants that change the hues of ripening fruits and cause leaves to change colors with the shortened days of autumn.

phytogenesis

The evolutionary development of plants.

phytogenic (syn. phytogenous)

Having a plant origin, e.g., coal.

phytography

The science of plant description.

phytology (adj. phytological)

The study of plants.

phytopathogen

An agent-causing disease in plants.

phytoplankton

Small, often microscopic, aquatic plants.

phytotoxicity (n. phytotoxin, adj. phytotoxic)

Being poisonous to plants.

pick

A mattock type tool, which has one or both ends pointed.

pick pruning

The selection of individual branches to be cut; the opposite of shearing.

pier

A mass of masonry used as a support, breakwater, etc.

pilose

Hairy, especially with soft hairs.

pilosulous

Minutely pilose.

pinna (pl. pinnae)

One of the primary divisions of a pinnate or compoundly pinnate frond or leaf.

pinnate

Consisting of several leaflets arranged on each side of a common petiole or rachis on a compound leaf or frond. 2. The feather vein pattern of simple leaves.

pinnately compound

With leaflets arranged in two rows along an axis.

pinnatifid (syn. pinnatipartite)

Divided in a pinnate manner, but with leaflets not entirely separate.

pinnatisect

Deeply cut, all the way to the axis.

pinnule

A secondary pinna; one of the pinnately disposed divisions of a pinna.

pip

1. The small seed of a fruit, like that of an apple or an orange. 2. An individual rootstock of lily of the valley or a similar plant.

pistil

The seed-bearing organ of the flower, consisting of the ovary, stigma, and style when present.

pistillate

Provided with pistils, and, in its more proper sense, without stamens.

pistillode

A sterile pistil, often rudimentary.

pitch

Lumps of resin found on the bark of trees.

pitcher-shaped

Campanulate, but with a distinct narrowing near the open end.

pith

The spongy or hollow center of twig or some stems.

pitted

Marked with small depressions or pits.

placenta

Any part of the interior of the ovary which bears ovules.

placentation

The arrangement of placentas within an ovary.

plankton

The floating or weakly swimming plants and animals occurring at any depth in bodies of water, often microscopic in size. See also: aeroplankton, edaphon.

plant

Any of the members of the kingdom Plantae typically lacking locomotive movement or obvious nervous or sensory organs and possessing cellulose cell walls and usually capable of photosynthesis.

plant labels

1. Plastic, wood, or metal stakes for gardens to indicate what seeds are planted where until they appear, and for varieties for evaluation. 2. Paper forms to include in drying plant samples, with formal printed forms as permanent labels on herbarium specimens. The minimum information required are the name of the collector, the location collected, the date collected, and hopefully, the correct identification of the specimen.

plant press (alt. field press)

A structure typically made of two ventilated frames 12 X 18 inches (30 X 45 cm.), within which plants may be arranged between sheets of driers and ventilators, tightly strapped together with press straps, in preparation of being added to a collection or herbarium.

plantation

A large farm of cultivated trees or plants, often of a single crop.

plantlet

A small plant, usually one produced vegetatively from a parent.

plasmodesma (alt. plasmodesm, pl. plasmodesmata)

One of the cytoplasmic strands that passes through openings in some plant cell walls and provide living bridges between cells.

plasmolysis

The shrinking of the cytoplasm away from the wall of a living cell due to the loss of water through osmosis.

plasticity

Flexibility; adaptability; capable of being repeatedly deformed without rupture.

plastid

Any of various cytoplasmic organelles of photosynthetic cells that serve in many cases as centers of special metabolic activities, e.g., chloroplasts.

plates

Flattened, rhizine-like structures on the lower surface of some lichens.

pleaching

A process whereby branches of woody plants are interwoven and plaited together to form an impassible hedge or very thick arbor. The only pruning done is to maintain a neat formal shape.

pleated

Describes a leaf creased along its length.

pleomorphic (n. pleomorphism)

Able to assume different forms.

pleurocarpous

Having the sporophyte lateral on a short lateral special branch. Pleurocarpous mosses can usually be recognized by the creeping habit.

plicae

Folds of a plicate leaf.

plicate

Folded into plaits, usually lengthwise.

plow

A device used to turn soil. On large farms several of these are mounted in a diagonal line, and referred to by the number of blades, e.g., a six-bottom plow. For compacted soil, chisels, four feet (1.3 m.) or longer, are used to open greater depth, and are called chisel plows.

plug

A core of grass sod or wildflower turf used in planting lawns and meadows.

plume

A feathery inflorescence.

plumose

Having fine hairs on each side, like the plume of a feather, as the pappus-bristles of some thistles.

plumule

The bud or growing point of the embryo.

plur- (alt. pluri-)

A prefix meaning many, e.g., plurilocular means many-celled.

plurilocular

Describes a sporangium or gametangium composed of many cells, each producing one zoospore or gamete.

pluriseriate

Many-ranked, as applied to leaves arranged in several rows along the stem.

pneumatophore

A specialized root in certain aquatic plants which performs respiratory functions.

pocket beach

The shore at a bay head where wave energy is lowest and settlings highest, often with fringe wetlands.

pod (syn. seedpod)

Any dry, several-seeded and dehiscent fruit.

podetium

A hollow upright structure.

polarity

The tendency for plants to develop from its poles, roots growing down, stems growing upward, making it essential to plant bulbs, etc, in the correct position.

pole pruner (syn. pruning stick, syn. pole saw)

A pruner on an extensible pole--usually having a curved saw at its end--which can be used to prune the upper parts of a tree or tall shrub.

pollarding

A process where tree tops are cut back severely each year to the same spots on the branches. This forces the growth of large knobby stubs from which long tender shoots grow each year.

pollen

The microspores of a seed plant contained in the anther, usually appearing as a fine dust.

pollen grain

A microspore of a seed plant.

pollen sac

The microsporangium of a seed plant where pollen is produced; the upper portion of the stamen containing pollen grains; the anther.

pollinate (n. pollination)

To transfer pollen from the anther of a stamen to the stigma of a pistil, resulting in fertilization. This can occur either on a single plant (self-pollination) or between different plants.

pollinator

The agent, such as an insect or wind, which carries the pollen for fertilization.

polliniferous

Bearing pollen.

pollinium (pl. pollinia)

A mass of waxy pollen or of coherent pollen grains, as found in Asclepias and Orchidaceae.

polyad

1. A set of molecular states connected by vibratory resonances. 2. A patented name for the adsorption process for the removal and destruction of Volatile organic compounds (VOC).

polybrid

A hybrid with more than two parental groups.

polyembryonic

Containing two or more embryos.

polyethylene

A plastic which allows the passage of gases but not of moisture.

polygamodioecious

Describes a plant group which has bisexual and male flowers on some plants, and bisexual and female flowers on others.

polygamous

1. Bearing male and female flowers on the same plant. 2. Having antheridia and archegonia disposed in various ways on the same plant.

polymorphic

Having more than two distinct morphological variants.

polypetalous

Having separate petals.

polyphyletic

Having members that originated, independently, from more than one evolutionary line. See also: monophyletic.

polyploidy (n. polyploid)

Having more than two sets of chromosomes in cells of the sporophyte or more than one set in cells of the gametophyte.

polysepalous

Having a calyx made up of separate sepals.

polystichous

Having leaves or other structures arranged in distinct rows.

polytrichous

Covered with many hairs.

polytypic

Containing more than one taxon of the next lower rank, e.g., a genus with more than one species. See also: monotypic.

pome

A kind of fleshy fruit, particularly an apple.

pompon

A small globular flower or flower head.

pond

A small, still body of water; an artificial body of water in a garden usually containing aquatic plants and fish.

pondweeds

A popular name for species of wetland plants that grow partially or wholly underwater.

pool

A small and relatively deep body of usually fresh water, either standing or as part of a stream. There is little wave action and often a reflective quality.

population

Plants of a species growing in a given place at a given time. Two similar species may mingle, e.g., Solidago canadensis and Solidago altissima, but the botanical term 'population' would include one species or the other, not both.

population density (syn. species density)

The concentration of individuals in relation to the space they occupy; how close individuals occur. See also: abundance, cover.

porate

Describes a pollen grain which has rounded apertures only. See also: colporate.

poricidal

A type of dehiscence in which the pollen is released through pores at the tip of the anther.

porose

Pierced with small holes or pores.

porrect

Spreading outward and forward.

Portland cement

A cement consisting predominantly of calcium silicates which reacts with water to form a hard mass.

positive drainage

Surface or underground pipes or trenches to remove excess water.

posterior

In an axillary flower, on the side nearest to the axis of inflorescence.

postreproductive

Refers to an organism which is past the age of breeding capacity.

potato fork

A fork of heavy construction with flat tines, for deep digging as is needed for potato harvesting.

potbound

The condition of a houseplant or outdoor container plant which has been left in the same pot or container for too long a period of time and the roots fill every niche of the pot or container. A hook or blade is required to cut through and separate the tangled matted outer roots when removed from the pot and before placing in the new container or the plant may never recover from this disastrous condition.

potential Hydrogen (abr. pH)

A log scale measurement of the acidity/alkalinity of a solution with 1 being extremely acidic, 10 being extremely alkaline, and 7 being neutral. Most plants prefer a soil within a certain range of pH.

potherb

A plant whose leaves, stems, or flowers are cooked or used as a seasoning.

pothole

1. A pond or pool utilized by waterfowl for nesting and raising young. 2. A hole worn in solid rock by the action of water, especially when a pebble repeatedly spins in the depression.

poultice

Moist, usually hot, mass of plant material; wrapped in a cloth and applied to the skin to bring about some desired action, such as bringing a boil to a head.

powdery mildew

A fungus forming a white powdery coating on leaves and stems.

power take off (abr. PTO)

Unit on a tractor to attach power tools.

Pozzolan cement

Volcanic rock powdered and used in making hydraulic cement.

pradines

Lopping tools.

praemorse

Appearing as if bitten off.

prairie

Grasslands, particularly that which formerly covered much of the central plains of North America, consisting of rich soil and a variety of grasses and forbs and generally covering a wide area.

precocious

Occurring early, as flowers appearing before the leaves; hysteranthous.

preemergent (alt. pre-emergent)

An herbicide, or combination fertilizer and herbicide, that is applied to a lawn early in the season, before the new growth has occurred.

prereproductive

Refers to a plant or animal which has not yet matured sexually.

prescribed burning

The intentional burning of plant material in an area. Sometimes used to consume underbrush and other fuel and thus prevent larger, more destructive fires. Also used to maintain a stable prairie or grassland by aborting the process of succession to shrubs and trees.

press straps (syn. web straps)

Bands or ropes to hold the plant press tightly together, traditionally made of web and buckles, but now often with Velcro.

prevernal

Appearing in late winter or very early spring, as do crocus flowers.

prickle

A small, sharp outgrowth involving only the outer epidermal layer, usually more slender than a thorn. This is the correct term for rose thorns.

primary forest (syn. natural forest)

A tract of trees with minimal impact from humans.

primocane

The floricane, but in the first year of growth before it is capable of flowering.

primordial utricle

The layer of protoplasm lying next to the cell wall, which is very often conspicuous when dried and shrunken.

primordium

A tissue or organ in the early stages when it has undergone differentiation changes but has not yet matured enough to emerge.

priority

The rule of nomenclature whereby the first published of two validly published names for the same entity is given approval as the accepted name.

prismatic

Of the shape of a prism, angular, with flat sides, and of nearly uniform size throughout.

pro hybrida (abr. pro hybr.)

Means "#as a hybrid."# Used in citations to show that a plant now known as a species started as a hybrid.

pro parte (abr. p.p.)

Means "in part". Used in citations to show that a taxon as used by one author shows only a portion of what was intended by the original author.

pro specie (abr. pro sp.)

Means "#as a species."# Used in citations to show that a plant which had been accepted as a species is now designated as a hybrid.

proboscis

Beak.

procumbent

Lying on the ground or trailing but without rooting at the nodes.

profundal zone

The area of deep water at the bottom of a lake below effective penetration of light. See also: abyssal.

projecting

Refers to stamens, styles, and stigmas which exert beyond the petals of a flower.

prokaryote (alt. procaryote, adj. prokaryotic, adj. procaryotic)

An organism composed of one or more cells lacking a visibly evident nuclei, including the viruses, bacteria, and cyanobacteria. See also: eukaryote.

proliferous (syn. proliferating)

1. Freely producing offshoots, bulblets, or plantlets. 2. In mosses, bearing young shoots from the antheridial or archegonial cluster of leaves.

prominent

Standing out from the surface, clearly visible and touchable, as are veins and other surface features.

prominulous

Slightly raised above the adjoining tissue.

propagate (syn. propagation)

To produce new plants, either by vegetative means involving the rooting or grafting of pieces of a plant, or by sowing seeds.

prophyll

1. The bracteole under a single flower or pedicel. 2. The showy first bract borne on the peduncle and, occasionally, on the inflorescence branches of some monocots.

prosenchymatous

Cells with pointed ends dovetailing into each other.

prostrate

Lying flat upon the ground.

protandrous

Refers to a flower where the shedding of the pollen occurs before the stigma is receptive. See also: protogynous.

protected area

A legally restricted land or water area under public or private ownership, which has managed to achieve specific conservation objectives.

proteinaceous

Of, relating to, resembling, or being protein.

proterogynous

Having the stigma ripe for the pollen before the maturity of the anthers of the same flower.

prothallium (pl. prothallia)

The minute scale-like growth from the spore of a fern.

prothallus

A cellular, usually flat and thallus-like growth, resulting from the germination of a spore, upon which are developed sexual organs or new plants. The gametophyte stage of ferns.

protogynous (syn. proterogynous)

Refers to a flower where the shedding of the pollen occurs after the stigma has ceased to be receptive. See also: protandrous.

protologue

Refers to all parts of botanical publication, including, but not limited to, diagnosis, description, synonymy, citation of specimens, illustrations, etc., expressed as data, information, and knowledge.

protonema

The green, branched, alga-like threads produced from the spore and often persistent during the lifetime of the plant produced from it.

protoplasm

The living contents of a cell.

protoxylem

The first formed xylem.

proximal

Toward the base.

proximate

Close together.

pruina

A woolly white covering of the upper cortex of some lichens.

pruinose

Having the surface obscured by a rather thick, bluish or grayish, wax-like coating.

prune

To cut back, for the purposes of shaping a plant, encouraging new growth, or controlling size.

pruning saw

A serrated blade tool for cutting small limbs; may be styled so the blade folds into the handle, or fit into a sheath.

pruning shears

Specialized scissors to cut plants back.

pseudanthium (pl. pseudanthia)

An inflorescence which looks like a simple flower, but is made of more than one axis with a number of flowers.

pseudobulb (adj. pseudobulbous)

A swelling at the base of a stem in which epiphytic orchids store nutrients and water.

pseudocarp (syn. accessory fruit, syn. false fruit)

A fruit, such as the strawberry or pear, that develops not only from the ripened ovary, or ovaries, but from nonovarian tissue as well.

pseudocyphellae

Pores found in the upper or lower cortex of lichens.

pseudolamina

A false lamina, one usually formed by the lateral expansion of a rachis.

pseudoparenchyma

Filamentous tissue compacted to resemble parenchyma.

pseudopodetium

An upright, fruticose thallus of some lichens.

pseudopodium

A leafless branch resembling a seta and often bearing gemmae.

pseudopods

Literally, false feet; a temporary protrusion of the protoplasm of a cell for the purpose of moving or feeding; foot-like organs.

pseudostem

An erect aerial growth which appears to be a stem with leaves, but is actually packed or overlapping sheaths and stalks of essentially basal leaves.

pseudoterminal

1. Describes a bud which is situated at what appears to be the apex of a branch, but is in fact located in an axillary position beside a leaf scar. 2. Refers to a bud which replaces an injured terminal bud which has died.

pteridology (n. pteridologist, adj. pteridological)

The study of ferns.

pteridophyte

Any of the nonflowering vascular plants of the division Pteridophyta having roots, stems, and leaves; a fern or fern ally.

Pterophyta

A major taxonomic division containing the ferns, showing clear alternation of generations with a dominant vascular sporophyte which begins with the very reduced gametophyte.

puberulose (alt. puberulent, alt. puberulous)

Minutely pubescent.

pubescence

A covering of soft, short hairs.

pubescent

Covered with hairs, especially if short, soft, and down-like.

puddle

1. A very small pool of water, often transitory, appearing during heavy rain and disappearing shortly afterward. 2. To knead or work soil while wet, making it impervious to water. 3. To work while wet, as in flooded rice fields.

Pulaski clearing axe (alt. Pulaski)

A tool used mostly by firefighters that is a combination of axe and grub hoe.

pulp

1. The soft, succulent part of a fruit, usually composed of mesocarp. 2. The pith of a stem.

pulpwood

The wood of trees like aspen, Populus, and spruce, Picea, which is easily ground into a soft mass for the production of paper.

pulverulent

Powdered; appearing as if covered by minute grains of dust.

pulvinate

Like a cushion.

pulvinus

A swelling at the base of the stalk of a leaf or leaflet.

punctate

Dotted with depressions or with translucent internal glands or colored dots.

puncticulate

Minutely punctate.

pungent

Terminating in a rigid sharp point; acrid to smell or taste.

purgatives

Medicines which empty the intestines.

pustular

Like a blister.

pustulate

Covered with blisters.

pustule

A surface eruption such as a pimple or blister.

putamen

The shell of a nut; the bony part of a stone fruit.

PVC sleeves

A plastic pipe used for moving water that acts as a conduit.

pycnidium (pl. pycnidia)

A rounded or flask-shaped asexual fruiting body containing spores found in certain fungi.

pyramidal

Conical with flat angular sides.

pyrene

The stone of a succulent fruit made up of the endocarp and the seed. See also: drupe.

pyriform

Pear-shaped.

pyxis

A capsule which opens in a circumscissile manner.

quadrate

Describes cells that are square or nearly so.

quadrifid

Divided into four parts.

quadrilateral

With four sides.

quadrinary combination

Binomial plus two more taxon names such as subspecies and variety.

quadripinnate

Four times pinnate.

quarantine

A legal ban on the export or import of certain noxious weeds or insects that may be attached to the plants.

quartered

Having the petals formed into a number of sections, usually four but sometimes three or five.

quinate

Having five leaflets growing from the same point of attachment.

quincunx (alt. quincunce, adj. quincuncial, adj. quincuntial)

The arrangement of five objects, such as trees, with one on each of four corners and one in the center.

raceme

A simple inflorescence of pediceled flowers upon a common more or less elongated axis.

racemiform

Refers to an inflorescence with the outward appearance of a raceme.

racemose

Resembling a raceme.

rachilla

The axis of a spikelet, particularly in grasses.

rachis

1. The main stalk of a flower cluster or the main leafstalk of a compound leaf. 2. In ferns, the continuation of the stipe through a compound frond.

radial

In flowers, one with the symmetry of a symmetry wheel.

radiate

Spreading from or arranged around a common center; bearing ray flowers.

radical

Belonging to or proceeding from the root or base of the stem near the ground.

radicle

The portion of the embryo below the cotyledons that will form the roots, more properly called the caudicle.

radicles (alt. rhizoid)

Rootlets springing from the sides and base of the stem.

radius (pl. radii)

1. The outermost flowers in a daisy-like head, Compositae; ray flowers as opposed to disc flowers. 2. The distance from the center of a circle to the outer edge, as from the heart of a tree to the bark.

raffia (alt. raphia)

A fiber-like material used for tying grafts and other horticultural purposes.

raised beach

An old beach terrace at an elevation above the present shoreline, representing a formerly higher lake level.

raised bed (syn. raised garden)

A bed or garden created by adding soil on top of that which is already present. This is usually done in cases where the underlying soil is particularly poor in nutrients or has inadequate drainage. Wooden or stone walls are often used to keep the added soil in place.

ramble

To grow freely, often over another plant or structure.

rameal

Belonging to a branch.

ramentaceous

Refers to stems or leaves which have small, loose, brownish scales.

ramet

1. An individual member of a clone. 2. An underground tree system giving rise to large suckering colonies, like big-tooth aspen trees, Populus grandentata.

ramification

Branching.

ramiflorous

Bearing flowers directly from large branches and leafless twigs, but not on the trunk.

ramiform

With branches; branch-like.

ramose

Having many branches.

ramuli

Minute branchlets.

ranch (alt. ranche, rancho)

1. In the united States and Canada, a farm that raises livestock, fruits, and vegetables for use of the family, or crops for feeding animals; sometimes used as a secondary income, e.g., a cattle ranch. 2. The buildings occupied or the persons on the estate (ranchers).

range of variation

The extremes of possibilities which may occur within a species and still remain a member of that species, including such things as leaf shape, leaf margins, flower color, height, etc.

rank

1. A vertical row, as of leaves. When you sight along the length of a branch from the tip end, if it appears there are two rows of leaves, either opposite or alternate, the branch is 2-ranked; if three rows, it is 3-ranked, etc. 2. In taxonomy, the position of a taxon in the hierarchy, e.g., species, genus, family, etc.

raphe

The part of the funiculus that is fused along the side of the ovule.

raphides

Needle-like crystals of calcium oxalate that occur in bundles in some plant cells.

ratchet tool

One which uses mechanical means to multiply cutting or turning power, reducing cramping of hands and forearms.

ravine

A depression worn by running water, larger than a gully and smaller than a valley.

ray

The branch of an umbel; the marginal flowers of an inflorescence when distinct from the disk.

ray floret

One of the broad, conspicuously colored florets of a compound flower, the structure of which suggests a single petal of an ordinary flower. These form the radiating border in the open-centered type dahlias, or massed together, the flower head in fully double types. See also: disc floret.

ray flower

The bilaterally symmetrical flowers around the edge of the head in many members of Compositae; each ray flower resembles a single petal.

rays

Radial strands of cells in wood and phloem.

recalcitrant seed

Seed that does not survive drying and freezing.

receptacle

1. The more or less expanded or produced portion of an axis which bears the organs of a flower (the torus) or the collected flowers of a head, and in roses, enfolds the developing ovaries to form a hip. 2. Any similar structure in cryptogams.

receptacular

Carried on the receptacle; pertaining to the receptacle.

recession

A drop in the water line of a body of water, with a corresponding exposure of the bottom.

reclinate

Bent or turned downward.

reclining

The lower portion somewhat flattened along the ground but the upper parts curving upward.

recurved

Curved downward or backward; with ray florets curved backward along their length toward the stem.

reeds

Tall thin wetland plants of the genera Phragmites and Sparganium; a term often incorrectly applied to bulrushes.

reel mower

A grass-cutting tool on which helical blades spin against a flat surface, generally hand powered but may be mechanized for a more precise cut than rotary mowers.

reference

A citation to a source of information, such as a written document.

reflexed

Abruptly bent or turned downward.

refrigerants

Herbal preparations which cool the body.

regular

Uniform in shape or structure.

regular flower

Generally symmetrical and uniform in the number of its parts.

rehabilitation

The process of improving specific ecosystem factors in a degraded habitat.

rejuvenation pruning

The practice of cutting all the main stems of a shrub back to within half-inch of the ground during winter dormancy.

relict (alt. relic)

A species or other group within a community that is representative of an earlier stage of development or of a different set of conditions.

relief

The difference in elevation between the highest point and the lowest point of land in a specified region.

remontant

Able to rebloom one or more times during a single growing season.

remote

Distant, at the farthest end.

renewal pruning

The practice of cutting all the main stems of a shrub back to within half-inch of the ground during winter dormancy.

reniform

Kidney-shaped.

repand

With a slightly uneven and somewhat sinuate margin.

repellent

A substance used to keep insects or animals from an area.

repent (alt. repen, syn. reptant)

Creeping; prostrate and rooting at the nodes.

replicates

Duplicate specimens.

replum

The hardened framework of the placenta which remains when the outer walls or valves of a silique fall away; the septum which holds the seeds.

resin

A plant secretion, often aromatic, that is insoluble in water but soluble in ether or alcohol.

resin dot

Tiny circular or globular yellow spots, usually not obvious except under magnification.

resiniferous

Producing resin.

resinous

Coated with a sticky gum or resin.

restoration

The return of an ecosystem or habitat to its original structure, natural complement of species, and natural functions.

resupinate

Turned upside down.

resupine

Refers to a flower or leaf on which the stalk twists a full half turn, 180 degrees, so that the organ appears to be upside down.

retardants

Admixtures that increase the setting time of cement by slowing down hydration.

retentive sepals

Sepals that remain attached to the apex of the receptacle after it has ripened into a hip.

reticulate

In the form of network; netveined.

reticulation

The entire network of reticulate veins, ribs, coloring and/or fibers.

reticulum (pl. reticula)

A mesh-like network.

retinaculum

The structure by which another structure is attached to a plant.

retrorse

Directed back or downward.

retting

Soaking plant tissue so as to induce bacterial growth that will aid in the separating of the fibers.

retuse

With a shallow notch at a rounded apex.

reversion

When a genetically differentiated plant or sport reverts to normal growth. For instance, variegated leafs turn green.

revolute

Rolled backward from the margins or apex; describing a ray floret with margins rolled backward along their longitudinal axis. See also: fully revolute.

rhachilla

A secondary axis; specifically, in the grasses and sedges, the floral axis as opposed to that of the spike or spikelet.

rhachis

The axis of a spike or of a compound leaf.

rhape

The ridge or adnate funicle which in an anatropous ovule connects the two ends.

rhaphides

Needle-shaped crystals often occurring in bundles within the cells of certain plants.

rhizines

Strands of hyphae found on the lower surface of many foliose lichens.

rhizobia

Bacteria in a symbiotic relationship with leguminous plants that results in nitrogen fixation.

rhizomatous

Having or appearing to have rhizomes.

rhizome (syn. rootstock, syn. understock, adj. rhizomatous)

Any prostrate or subterranean stem, usually rooting at the nodes and becoming erect at the apex.

rhizome chaff

Small pieces of rhizomes which are spread upon the ground and covered with soil so they can take root and form new plants.

rhizome cutting

A piece cut from a rhizome which can take root and form a new plant.

rhizosphere

The area that surrounds and is influenced by a plant's roots.

rhombic

Diamond-shaped.

rhomboid

Refers to leaves, tepals, etc., which are diamond-shaped, with the base and tip having acute angles and the sides having obtuse angles.

rib

A primary or prominent vein of a leaf.

ribbed

With one or more prominent veins or nerves.

ribs

Geologic ridges running parallel, as often occurs along a mountain side.

ridged

Angular, with lengthwise lines.

rind

1. The bark of a tree outside the cambium layer. 2. The epicarp of a citrus fruit, e.g., an orange or a lemon.

ringed

Having narrow encircling stipule scars around leaf scars.

ringent

Gaping, as the mouth of an open bilabiate corolla.

riparian

Of, or relating to, rivers or streams.

ripening

1. The maturing of a fruit as developmental changes prepare it for seed dispersal. 2. The hardening of wood, especially of soft twigs, important in taking cuttings for propagation.

risers

The up and down sections of stair steps; necessary for landscape plans.

riverine

Refers to a river.

rivermouth

The place where a river empties into another body of water.

rock garden

A garden laid out among rocks and adapted for the growth of particular kinds of plants, such as alpines.

rolled

Curled under; revolute.

root

The underground part of a plant that serves to anchor it and supplies it with nourishment.

root cutting

A cutting taken from the root of a parent plant for the purpose of propagation.

root knot

A disease of the roots characterized by a swelling and caused by nematodes.

root pruning

1. Pruning to stimulate the growth of new roots within a parameter in preparation for transplanting. 2. Trimming and/or scoring the outer layer of roots of a plant that has become root bound. 3. The act of removing a portion of a plant's roots to keep top growth in check.

root zone

The area immediately surrounding the roots and from which a plant takes moisture and nourishment.

rootball (alt. root ball)

The root stock and surrounding soil together; in nurseries and during transport, these are held together by burlap or other wrapping.

rootbound (alt. root bound)

The condition of a houseplant or outdoor container plant which has outgrown its container, with the roots filling every niche of the container. Eventually, the roots will themselves strangle the plant by constricting the flow of nutrients. A hook or blade is required to cut through and separate the tangled matted outer roots when removed from the pot and before placing in the new container.

rootlet

A small, secondary root.

rootstock (syn. rhizome, syn. understock)

1. A rhizome. 2. The root system and lower portion of a woody plant to which a graft of a more desirable plant is attached.

rootworm

The larvae of a beetle of the genus Diabrotica that feed on the roots of various plants, particularly corn.

roridulous (alt. roridulate)

Dewy; covered with waxy plates which appear to be dew drops.

rose dethorner

Florist tool to remove the thorns from roses and other flowers.

rose hip

A smooth, rounded, fruit-like structure consisting of the cup-like calyx enclosing seed-like fruits.

rosette

A cluster of leaves which grows in a circular overlapping pattern--somewhat like the petals of a rose--arising basally from a crown, as on a dandelion, or apically from an axis, as on many palms.

rostellate

Having a short beak.

rostellum

A little beak: a slender extension from the upper edge of the stigma in orchids.

rosula

A rosette.

rosulate

In the form of a rosette.

rot

Any of various diseases causing the breakdown and rotting of tissue.

rotary edger and trimmer

A lawn tool which has rotating spikes on one edge to trim grass back from drives and walks.

rotary mower

The most common type of grass-cutting tool, usually powered by gasoline or electricity.

rotate

Describes a corolla that is wheel-shaped flat and circular in outline.

rotation grazing

Alternating between two or more pastures. See also: cell system pasturing, deferred grazing.

rotund

Rounded.

rough

Papillose

rubefacients

Herbal medicines which open the small blood vessels of the skin to increase its heat and redness.

ruderal

Growing in poor land or waste places.

rudimentary

Partially developed.

rufescent (alt. rufous)

Reddish-brown.

rugulose

Covered with minute wrinkles.

ruminate

Having a surface which is coarsely wrinkled, appearing as though chewed by a cow and then spit out, but not with the margins appearing gnawed as in erose margins.

runcinate

Sharply incised, with the segments directed backward.

runner

A filiform or very slender stolon. A prostrate branch that roots at its joints.

runoff (alt. run-off)

Water which originated on top of the land, such as rain, and collected beyond the ability of the soil to absorb it, so it flows away.

rush (pl. rushes)

Any of various monocotyledonous, grass-like, often tufted marsh plants of the family Juncaceae, having cylindrical often hollow stems.

rust

A large fungus group infecting such plants as roses and snapdragons. Round spots occur on the leaves, filled with yellow or reddish spores.

rusticate (n. rustication)

To build or face with usually rough-surfaced masonry.

saccate

Sac-shaped.

sagittate

Shaped like an arrow-head, the basal lobes directed downward.

salinity

Refers to an excess of salts in the soil which causes leaves to scorch and turn yellow and does great harm to many plants.

salver-shaped

Describes a corolla that has a slender tube abruptly expanded into a flat limb.

salverform

Having a slender tube which expands abruptly.

samara

A dry, one-seeded, indehiscent winged fruit; a key.

samaroid

Resembles a samara, a winged fruit.

sandbar (alt. sand bar)

A temporary ridge of sand formed by currents in a body of water.

saponin

A glycoside compound of plants which has a foaming or soap-like action.

saprophyte

A plant lacking chlorophyll and living on dead organic matter.

saprophytic

Feeding from dissolved or decayed organic material, as a saprophyte.

sapwood

The more recently produced, outer layer of wood tissue of a tree, usually lighter in color than the heartwood.

sarmentose

With long slender stolons.

saturation cratering

Ancient land around a volcanic area, filled with old and new craters from repeated eruptions.

savanna (alt. savannah)

A flat grassland of tropical and subtropical regions usually having distinct periods of dry and wet weather.

saxatile (alt. saxicolous, alt. saxicoline)

Growing among or upon rocks.

scaberulous

Slightly scabrous.

scabrid

Minutely rough.

scabridulous

Slightly rough.

scabrous (syn. scabrid)

Rough to the touch.

scaffold branches

The main side branches of a tree, especially a fruit tree.

scalariform

Having a ladder-like pattern.

scale

1. A thin, membrane-like covering of the bud or twig base. A fine, grain-like surface material. 2. Sap-feeding insects that live under shell-like scales on stems, bark, and leaves.

scale leaves

Specialized leaves, including those covering buds or composing bulbs.

scales

The chaff on the stems of ferns.

scaly

Having tiny scales attached at only one end.

scandent

Climbing, but not self-supporting.

scape

A peduncle rising from the ground, naked or without proper foliage, e.g., a dandelion; the leafless stem of a flower.

scapose

Bearing or resembling a scape.

scarify (n. scarification)

To scar or nick the seed coat to enhance germination.

scariose

Scarious, having thin, dry, shriveled tissues.

scarious

Thin, dry, and membranaceous, not green.

scarred

Having marks where organs have fallen off, such as leaf scars on stems.

schizocarp

A fruit that splits between carpels into one-seeded portions or lobes.

scientific name (syn. botanical name, syn. technical name)

The name applied to a plant, animal, or other organism, according to the Codes of Nomenclature. Although in some cases a scientific name is changed; it is almost always a much more reliable manner of identifying a plant than the often variable common name. See also: binomial.

scion

A cutting from the upper portion of a plant that is grafted onto the rootstock of another plant, usually a related species.

scion rooting

Covering a low graft with soil so that the plant develops roots directly from both the rootstock and the scion.

scion wood

Shoots from which graft scions are cut.

sclereid

A variably shaped sclerenchymatous cell of a higher plant.

sclerenchyma (adj. sclerenchymatous)

Tissue composed of cells with thickened and hardened walls.

scleromorph

A plant with leaves and/or stems that are hard, usually having a thick cuticle. See also: xeromorph.

sclerophyll

A woody plant with small, leathery, evergreen leaves and generally found in hot, dry climates. See also: chaparral, fynbos.

sclerophyllous

Having leaves stiffened by sclerenchyma.

sclerotium

A dense mass of filaments comprising the dormant phase of certain fungi.

scoop shovel

A shovel with a very large blade, often made of thin light-weight metal or plastic, used for moving large amounts of crops such as ear corn, or clearing water.

scorch

The drying and browning of leaf margins usually caused by unfavorable environmental conditions.

scorpioid

Describes an inflorescence that is circinately coiled while in bud.

scrambler

A plant with long stems, often with thorns to help it support itself as it climbs through shrubs.

scree

Fragmented rocks usually found at the base of a cliff or boulder where the action of wind and water has broken the particles loose. Scree may be used in gardens as a mulch.

screen

A single plant or grouping of plants used to bar certain parts of the landscape from view.

scuffle hoe

A medium-weight hoe with the blade fastened to the handle in the middle of the horizontal blade, allowing it to be pushed and pulled, cutting weeds on each direction.

scutate (alt. scutellate)

Platter-shaped, with a flat center and raised margins, as a water lily leaf, Nymphaea lotus.

scutelliform

Shaped like a small shield.

scythe

A long-handled blade for making grass into hay; the term is sometimes used for the blade without the handle. See also: snath.

seawater

Ocean water with a high salt content.

secateur

Hand-held pruning shears.

secondary species

The species subordinate to the dominant species, like dogwood, Cornus, in an oak, Quercus, forest.

sectio (alt. section)

The category of supplemental taxa at a rank between subgenus and series.

secund

Twisted or turned to one side.

sedatives

Medicines which can slow certain bodily functions and promote sleep.

sedge

Any of the grass-like, monocotyledonous plants of the family Cyperaceae, having achenes and solid stems wich are triangular in cross-section.

seed

The ripened ovule, consisting of the embryo and its proper coats.

seed coat

The outer protective covering of a seed.

seed drill

1. A shallow trench in which to sow seeds. 2. An implement for planting seeds.

seed fern

Extinct fern-like plants that bore seeds on the frond.

seed leaf

A cotyledon.

seed lot

Seeds of a particular crop gathered at one time and likely to have similar germination rates and other characteristics.

seedbank

A facility designed for the ex situ conservation of individual species and varieties through controlled seed storage.

seedbed

An area cultivated for planting seeds.

seedhead

The dry fruit containing rip seeds.

seedling

A young plant grown from a seed.

segment

1. One of the parts of a leaf or other like organ that is cleft or divided.

segregate

1. A new genus culled from an established one for taxonomic reasons. 2. A hybrid which exhibits the genetics of one of the parents more clearly than those of the other parent.

seiche

A rapid and sometimes violent fluctuation in water level within a landlocked body of water, usually due to sudden changes in barometric pressure, the ripples lasting from minutes to several hours. See also: tsunami.

selection

A distinct form of a plant, sexual or asexual in origin, selected and propagated for monetary reasons or beauty, and named as a cultivar.

selective felling (syn. selective cutting)

When only choice trees are cut in a forest.

self

Having a single pure color with no markings.

self-clinging

Refers to plants which climb rocks or structures without the support of other plants, perhaps by suckers or tendrils.

self-fertile

Able to be pollinated by its own flowers.

self-pollination

The transfer of pollen from the anther of a flower to the stigma of the same flower, or to different flowers on the same plant.

self-seeding

Produces offspring from seed without intervention.

self-sowing

Produces offspring from seed without intervention.

semelparity

Refers to an organism that has a single reproductive season and then dies. See also: iteroparity.

semi-

Prefix meaning half or partly.

semidouble (alt. semi-double)

Having more than the usual number of petals but with at least some pollen-producing stamens.

semievergreen (alt. semievergreen)

Retaining at least some green foliage well into winter, or shedding leaves only in cold climates.

semihardwood cutting

A cutting taken from a stem that has just begun to develop woody tissue, for the purpose of propagation.

semihardy

Questionably hardy in a given temperature zone; susceptible to damage by extreme cold or heat.

semirotate

Saucer-shaped, almost flat.

semiterete

Refers to a cylinder which is rounded on one side, but flat on the other, as some leaf petioles.

senescence

The process of aging in a plant or plant part (as a leaf) from full maturity to death.

senescent

Dying of tissues following maturity.

sensu

Meaning "in the sense of" in taxonomy.

sepal

A division of a calyx; one of the outermost circles of modified leaves surrounding the reproductive organs.

sepaline

Refers to sepals.

sepaloid

Like a sepal.

sept

A small dent or cavity.

septate

Divided by partitions.

septicidal

Describes a capsule that is dehiscing through the partitions and between the cells.

septifragal

Describes the dehiscence of a fruit where the valves or backs of the carpels break away leaving the septa intact.

septum (pl. septa)

Any kind of partition.

sere

The complete cycle of changes from the original state to the climax condition, e.g., oak-maple forest, forest destroyed by fire, meadow, brushland, young mixed conifer-deciduous forest, oak-maple forest.

seriate

In a whorl or row, generally preceded by a number or numerical prefix, as triseriate meaning in three rows.

sericeous

Bearing fine, usually straight, appressed, hairs.

series

A group of similar, but not identical, plants.

serotinal

Appearing in the autumn or late summer.

serrate

Having sharp teeth pointing forward.

serrulate

Finely serrate.

sessile

Without footstalk of any kind.

set

1. The development of fruit, and or seed, following pollination; to set seed. 2. To transplant as seedlings. 3. To apply as a graft. 4. A young bulb, tuber, or other type of vegetative propagule ready for planting. 5. Transformation of cement paste or concrete from a fluid-like consistency to a stiff mass.

set seed (alt. go to seed)

To produce seeds after flowering. In some cases a gardener wishes to prevent this in an effort to prolong flowering, or continue harvesting the foliage of an herb.

seta

1. A bristle. 2. In mosses, the stalk holding the spore capsule.

setaceous

Bristle-like.

setiform

Bristle-shaped.

setose

Beset with bristles.

setulose

Having minute bristles.

sextant

An instrument used mostly at sea, where there are no bench marks, to determine location by latitude and longitude.

shade (adj. shady)

Light diminished by some blocking feature. See also: light shade.

shade tree

A larger tree planted in a location where the canopy provides shade at ground level.

sharp sand

Coarse sand used to loosen heavy soil and in construction, as opposed to the more finer grained play sand.

sharp-pointed

Acute, mucronate, pungent.

sheath

A tubular envelope, as the lower part of the leaf in grasses.

sheathing

Enclosing as by a sheath.

shoot

A young, actively growing twig or stem.

short-lived

Describes a plant, usually perennial, where the individuals live for only a few seasons.

shovel

1. A long-handled scoop-like implement used for digging, lifting, and throwing, etc. 2. The quantity contained in one scoop.

shrub

A woody perennial, smaller than a tree, usually with several stems.

shrublet

A dwarf woody plant.

sialagogues

Herbal medicines that can increase the flow of saliva.

sickle

1. A short-handled hand tool similar to a scythe but smaller and curved into a semicircle, used to cut heavier crops like corn, Zea mays.

sickle bar

A mechanical cutting tool that fastens onto a tractor's power source.

sigmoid

Curved like the letter S.

siliceous

Containing silica.

silicle (alt. silicula, alt. silicule)

A short silique, no more than twice as long as it is broad.

silique (syn. siliqua)

A dry, dehiscent, elongated fruit formed from a superior ovary of two carpels, with two parietal placentas and divided into two loculi by a false septum between the placentas, occurring in plants of the family Cruciferae.

silky

Covered with close-pressed soft and straight pubescence.

silt

Fine-grained sediment usually 1/20 millimeter or less in diameter, finer than sand particles and coarser then those composing clay.

silt load

The particles finer than sand which are carried in a suspended state in moving water. See also: bed load.

silviculture

The cultivation and care of forest trees.

simple

Of one piece; not compound.

simple fruit

A fruit developed from a single ovary.

simple leaf

A leaf with an undivided blade.

single

1. A single flower. 2. Describes varieties having only one bloom per stem.

single flower

A plant containing the normal number of petals. Double flowers often have multiples of the normal number: 6 or 9 for three-petal flowers, 8 or 12 for four-petals flowers, etc.

single-worked

Grafted only once so that the grafted plant consists of rootstock and scion.

sinuate

With the outline of the margin strongly wavy.

sinuous

Wavy like the path of a snake.

sinus

The cleft or recess between two lobes.

skeletonized

Refers to a leaf which has only ribs and veins left, the soft tissue having been consumed by insects or bacteria.

skeletonizer

Any of various lepidopterous larvae that eat the parenchyma of leaves reducing them to a skeleton of veins.

skylight

The diffuse and reflected light of the sky. See also: direct sunlight.

sludge

Precipitate of solids from water or sewage treatment, which may or may not contain harmful compounds; generally composted for a year or two before applying as organic fertilizer.

slump test

A test used to determine workability of cement or concrete.

small fruits

Those species which produce edible fruits, but do not grow on trees, e.g., strawberries and blueberries.

smoke jumper

A trained firefighter who is dropped from an airplane in the path of a wildfire to attempt to control the blaze.

smooth

Without roughness or pubescence.

snag

1. Part of the rootstock left during a graft to hold the scion in place. 2. Removal of the projection when the scion no longer needs it. 3. A rough projection on a woody plant which needs to be removed.

snath

The handle of a scythe.

snow fencing

Wooden or plastic lath joined by wire into long rolls, then erected 100 feet (33 m.) or so on the windward side of a road or barnyard. The lath breaks the velocity of the wind allowing snow particles to drop before reaching the road. It may also be used as a shade cover for plants.

sobole

A shoot, especially from the ground.

soboliferous

Bearing soboles.

social dominance

The control of behavior of those animals lower in the hierarchy, by aggression, intelligence, or other factors of the alpha animals.

social facilitation

The effect of the closeness of one organism upon the conduct of another one.

sod coring tool

A lawn tool which removes spikes of soil, about one half inch (1 cm) in diameter, to allow air and water to penentrate. See also: aerator.

sod planter

A lawn tool which cuts a hole of about 2 inches (5 cm.), releases the core with a hand or foot system, picks up a new sod block and inserts it.

sodic

Of, relating to, or containing sodium.

softwood

The immature stems of woody plants. Also, term applied to conifers as opposed to the broad-leaved trees, or hardwoods.

softwood cutting

A cutting taken from a green or immature stem of a woody plant, for the purpose of propagation.

soil

1. The top layer of the earth's surface, consisting primarily of clay, sand, silt, and organic matter. 2. Any natural or synthetic substance or medium in which plants may take root and grow.

soil amendment

Substance added to soil to increase its nutritive value, friability, moisture retention, or some other aspect.

soil cuber (alt. soil blocker)

Hand-held device into which moist soil is packed, then released in the form of a cube or block in which a single seed is planted.

soil fixation

The conversion of a soluble substance such as phosphorus from the exchangeable form useful to plants, to a relatively insoluble form.

soil sampler

A hollow tube with a T handle, which is pressed into the soil to get a core of the horizon.

soilless mix

A potting soil that uses sand, bark, and/or other ingredients, but not any actual soil.

solid

Smoothly pithy, the twig center neither chambered nor hollow.

solitary

Borne singly or alone; not in clusters.

solutio (abr. sol)

Latin term for a solution.

somatic

Belonging to the vegetative part of a plant as opposed to the reproductive.

soralium (pl. soralia)

A clump of soredia.

soredium (pl. soredia)

A microscopic clump of agal cells surrounded by the hyphae of fungi and erupting at the surface of the thallus.

sorus (pl. sori)

An assemblage of sporangia; a fruit dot.

spacing

Measured distance between the center of one plant and the center of the next closest ones.

spade

A digging implement, foot powered, usually of heavier construction than a shovel and often with a flat end.

spadix

A flower spike with a fleshy axis, usually enclosed in a spathe.

spartoid

Rush-like, but sharp and rigid.

spasmolytic

Describes an herbal preparation that can ease cramps or spasms.

spathaceous

Resembling or having a spathe.

spathe

A sheathing bract or pair of bracts partly enclosing an inflorescence and especially a spadix on the same axis.

spatheole

A small or secondary spathe.

spathiform

Shaped like a spathe.

spatulate (alt. spathulate)

Gradually narrowing downward from a rounded summit; spoon-shaped.

species (abr. sp., pl. spp.)

A fundamental category of taxonomic classification that ranks below a genus and above subspecies; a population or series of populations whose individuals have the potential to freely breed with one another and that is discontinuous in variation from other populations or series of populations. The plural abreviation "spp." is usually used to refer to all the individual species within a genus, e.g., Cornus spp. refers to all the plants within the dogwood genus.

species diversity

Almost the same as species richness, but in more technical literature, an ecosystem that is said to be more diverse if the species present have equal population sizes and less diverse if many species are rare and some are very common.

species richness

The number of species within a region. See also: species diversity.

specimen (pl. specimens)

1. Item considered typical of its class, e.g., an herbarium specimen. 2. Plant grown for landscape exhibition, e.g., a specimen tree.

specimen preparation

The collection, selection, arrangement, pressing, drying, and mounting of a plant for an herbarium specimen, allowing many specimens to be stored in minimal space.

specimen tree

A tree placed so people can gain the greatest enjoyment for the color, texture, scent, or other pleasures it provides.

spermatium (pl. spermatia)

The nonmotile male cell of red seaweeds; also used for similar cells in fungi.

spermatocyte

A cell which gives rise to sperm cells.

Spermatophyta

A major taxonomic division containing all plants which reproduce by seed, subdivided into Gymnospermae and Angiospermae.

spermatophyte (syn. seed plant)

Any plant of the division Spermatophyta, the higher plants that produce seeds, including the gymnosperms and angiosperms.

spermatozoid

A motile ciliated male reproductive cell.

sphagnum moss

Bog mosses that are often used as soil additives and packing material because of their ability to retain moisture. See also: peat moss.

spherical

Nearly round.

spicate

Arranged in or resembling a spike.

spiciform

Spike-like.

spiculate

Having fine fleshy points.

spider mite (syn. red spider)

Any of several small, red, web-spinning mites of the family Tetranychidae that feed on and damage leaves.

spike

A form of simple inflorescence with the flowers sessile or nearly so upon a more or less elongated common axis.

spike harrows

A field implement with spikes that breaks up clods and levels soil.

spikelet (syn. earlet)

A small or secondary spike, most often refiring to those forming the inflorescence of grasses.

spindle-shaped

Same as fusiform.

spine

A sharp woody or rigid outgrowth from a stem, leaf, or other plant part.

spinescent

1. Having spines. 2. Terminating in a spine. 3. Modified to form a spine.

spinose

Spine-like, or having spines.

spinulate

Having spinules.

spinule

A minute spine or spine-like process.

spinulose

Thorny; set with small spines.

spired

Having a crown with several points.

splitting maul

An axe with a broad, heavy head, shaped into a wide nonstick wedge.

spoils

Soil from stream or drain bottoms dredged out when the channel was made deeper.

sporangiophore

A specialized stalk bearing a sporangium.

sporangium (pl. sporangia)

A tiny globe in which the spores are produced; often applied to the capsule, but by some authors restricted to the spore sac, or inner sac of the capsule containing the spores.

spore

The reproductive organ in cryptogams which in function corresponds to a seed but possesses no embryo.

sporecase

Same as sporangium; the case in which the spores are borne.

sporocarp

The fruit cases of certain cryptogams containing sporangia or spores.

sporogenesis

Reproduction by means of spores.

sporogenous

Describes cells or tissues in which spores are formed.

sporophyll

A leaf bearing spores.

sporophyte (syn. sporophore)

1. The spore-bearing part or generation. In mosses, it consists of the seta and capsule and constitutes the so-called fruit. In ferns, the conspicuous plants that bear spores.

spororogonium

The sporophyte or spore-bearing part of the moss.

sport

An abrupt, naturally occurring genetic change resulting in a branch that differs in appearance from the rest of the plant, or, a plant derived by propagation from such a genetically changed branch.

spreader

1. A lawn cart that applies seed, fertilizer, etc. 2. A large wagon used on organic farms to apply manure to the fields.

spreading

Having a horizontally branching habit.

sprig

A small part of a plant, such as stolons used for propagations, twigs bearing flowers, etc.

spring wood

Wood which is formed during the period of rapid growth in the spring, appearing lighter in color than the wood formed later as the growth slows down.

spud (alt. ice spud)

A tool shaped like a flat-ended oar that is used to chop a hole through ice for fishing or studying underwater biology, but which may also be used to clear ice from sidewalks, cut sod or roots, edge sidewalks, etc.

spur

A hollow sac-like or tubular extension of some part of a blossom, usually nectariferous. Also, a short, slow-growing branchlet.

spur branch

A stubby branchlet with densely crowded leaves and leaf scars.

spurred

Calcarate; refers to a flower with tubular projections from the petals or sepals, usually with nectar glands.

sqarulose

Diminutively squarrose.

squamate (alt. squamose, alt. squamous)

Covered with scales.

squamulate

Having squamules.

squamulose

Having small scales.

squarrose

Turned back at a right angle or more sharply, as the tip of a phyllary.

stability

Resistance to variation in populations and disturbances, resulting in the persistence of community composition over long periods of time.

staddle

A foundation of trunk and main branches, either of rootstock or stembuilder, for grafting.

staking

Providing support for newly-planted trees or tall plants by tying the plant to one or more stakes planted beside and parallel to the plant.

stalk

A short, supporting axis.

stalked

Joined to an axis with a stalk.

stamen

One of the male, pollen-bearing organs of the flower.

staminal

Attached to or referring to the stamen.

staminate

With stamens and without pistils.

staminode (syn. staminodium, syn. staminoide)

A sterile stamen, or any structure without anther corresponding to a stamen.

staminoid

A pollenless stamen.

standard (syn. banner)

1. A plant with a strong vertical stem, particularly one that would not normally grow that way; a vine or shrub trained as a tree with a single trunk and a more or less spherical top. 2. Uppermost, usually erect, petals of some flowers; the upper dilated petal of a papilionaceous corolla.

stegocarpous

Having the capsule operculate.

stele

The axial vascular and associated tissues from the endodermis inward.

stellate (syn. stelliform)

Star-shaped.

stem

The main ascending axis of a plant.

stembuilder

A variety of woody plants used in a graft as intermediate stem piece to provide a strong trunk for standard trees, or to introduce resistance to disease or winter injury.

steppe

A vast arid, usually level and grassland, particularly those of southeastern Europe and Asia and generally having extreme variations in temperature. See also: pampas, prairie.

stereids

The small thick-walled cells seen in.

sterigma (pl. sterigmata)

The spike on which a fungus spore is home.

sterigmata

The small woody stem to which the leaves of spruces and hemlocks are attached.

sterile

1. Barren. Refers to fern leaves that do not produce spores. 2. Unproductive, as a flower without a pistil, or a stamen without an anther.

stichidium

A small structure (lobe or branch) bearing tetrasporangia.

stigma

That part of a pistil through which fertilization by the pollen is affected.

stigmatic

Belonging to or characteristic of the stigma.

stigmatose

With conspicuous stamens.

stigonema

A filamentous blue-green algae.

stilt-roots

Adventitious support roots.

stimulants

Herbal medicines that can increase the energy or activity of a tissue, organ, etc.

stipel

A stipule of a leaflet.

stipellate

Having stipels.

stipitate

Having a stipe or short stem.

stipular

Belonging to stipules.

stipulate

Having stipules.

stipule

An appendage at the base of a petiole, often appearing in pairs, one on each side, as found on roses.

stipule scar

The scar left on a twig by the fall of a stipule.

stock driveway

A lane; a strip of land designated for the movement of livestock.

stock plants

Mother plants kept for cuttings to reproduce the plant.

stoloniferous

Producing stolons.

stoloniferous stem

A slender creeping stem with minute leaves.

stoloniform

Like a stolon, underground stem.

stoma (pl. stomata)

1. An orifice in the epidermis of a leaf communicating with internal air cavities. 2. A pore in the wall of a capsule surrounded by special guard-cells and serving the same purpose as the stomata in the epidermis of the leaves of flowering plants.

stone (alt. stone fruit)

The single seed of a drupe, surrounded by a large, hard shell and covered by pulp.

stool

Clump of shoots growing from near the ground.

stooling

Cutting down to ground level to induce tightly packed new growth.

stopping

Pinching off the terminal bud to induce branching.

storm surge

Before and during a storm, an abnormal and rapid rise in lake level along the shore, caused mostly by strong onshore winds and changes of atmospheric pressure.

stove

A heated greenhouse.

straggling

Semiupright.

straight

Describing ray florets having little or no curvature throughout their length (used in describing dahlias.)

strain

A number of plants which have similar characteristics such as color blends, different enough to be designated, but not sufficiently distinct to be considered a horticultural variety.

stramineous

Straw-colored.

strand

1. The area of lakeshore above the waterline that is subject to the action of wind and rain. 2. On ocean beaches, the area between high and low tidal marks.

stratified

Having prominent horizontal layers.

stratify (n. stratification)

Artificially overcoming a seed's dormancy by placing them in layers of moisture-retaining media and keeping them under generally cool and moist conditions for a period of time, so as to simulate winter conditions.

strawflowers

Species of plants which easily become dried flowers.

stria (pl. striae)

A thin ridge or groove.

striate (syn. striated)

Marked with fine, longitudinal lines or ridges.

strict

Very straight and upright.

strigose

Beset with appressed sharp straight and stiff hairs.

strigulose

Minutely strigose.

string tags

Waterproof tags used to mark collected specimens for herbarium study.

striolated

With delicate lines or ridges.

strip cropping

A method of planting a crop in parallel bands following the contours of the slope; this lessens erosion. See also: field strip cropping, filter strip.

strobiloid (alt. strobiliform)

Cone-shaped.

strobilus (alt. strobile)

1. Woody cone, as in Gymnospermae. 2. A cone-shaped inflorescence marked by imbricated sporophylls. 3. A dense cone-like structure producing spores.

stroma

1. A compact mass of fungal hyphae producing perithecia or pycnidia. 2. The colorless proteinaceous matrix of a chloroplast in which the chlorophyll-containing lamellae are embedded.

strone (alt. stron)

A hill that terminates a ridge; the end of a ridge.

strophile

An appendage at the hilum of certain seeds.

strophiole

Resulting from an inverted ovary that has fusion of the nucellus and funiculus. The strophiole is a small swelling on a ridge.

struma

A goiter-like swelling on one side at the base of the capsule.

strumose

Having a struma.

stunt virus

A type of virus disease which stops the growth of a plant.

stylar (alt. styled)

Either having styles or found on a style.

style

The usually attenuated portion of the pistil connecting the stigma and ovary.

stylopodium

A disc-shaped enlargement found at the base of the style in some Umbelliferae.

styptic

A medicine to stop minor surface bleeding, e.g., razor cuts.

sub-

A prefix meaning somewhat or physically below.

subarctic

Of, relating to, or being the regions bordering on the arctic zone.

suberect

Ascending toward the edges.

suberin

A complex fatty substance found especially in the cell walls of cork.

suberization (adj. suberized)

The conversion of the cell walls into corky tissue, called suberin.

suberous

Cork-like.

subgenus

An intermediate category in taxonomy between genus and species.

subimbricate

Somewhat overlapped; slightly shingled.

submergent vegetation

Plants with stems and leaves below water level, sometimes with reproductive parts above water.

submersed (alt. submerged)

Underwater.

subopposite

Almost opposite but one leaf or leaflet of each pair a little above the other.

subsessile

With a slight stalk.

subshrub

A plant with more or less woody branches and roots, less woody than a true shrub, but more woody than a perennial herbaceous plant; a small shrub, woody only at the base.

subspecies (abr. ssp.)

The rank of taxa below species but above variety; a subdivision of a species whose members have certain hereditary characteristics distinct from other populations of that species. A subspecies is added to the specific binomial and preceded by "#ssp.", such as obtusifolia in the epithet Grevillea thelemanniana ssp. obtusifolia.

substratum (syn. substrate)

The material on which a plant grows.

subtend

To be just below and close up to or enclosed in its axil.

subterranean

Below ground.

subtropical (syn. semitropical)

Of, relating to, or being the regions bordering on the tropical zone.

succession (syn. biotic succession)

1. The development of a plant community from its initial stage to its climax stage; usually from one consisting of grasses and forbs to one of shrubs and, finally, to forest. However, depending on the climate, the climax stage may consist of a prairie, savana, or any number of other ecosystems. 2. The changes in the species composition of communities following a natural or human disturbance like the natural filling of a pond or the clearing of a road through a forest.

succulent

A plant having fleshy stems or leaves, often adapted to xeric conditions.

sucker

A shoot from the root or lower part of a stem. In roses, a young cane emerging below the bud union and therefore representing the variety of the understock rather than the top variety. A shoot appearing on a tree limb is called a water sprout.

suffrutescent

Slightly or obscurely shrubby.

suffruticose

Very low and woody; diminutively shrubby.

sulcate

Grooved or furrowed.

summer wood

Wood produced late in the growing season when growth is slow.

sunken garden

A garden recessed into the ground to create a secluded atmosphere or to facilitate a view down onto a feature such as a knot garden.

super- (alt. supra-)

A prefix meaning above, greater than, superior to.

superficial

On the surface.

superior ovary

With the flower parts growing from below the ovary.

superparasitism

Parasitization of a host by more than one individual, usually of a single species.

superphosphate

A fertilizer with a very high amount of phosphates, uusally 30-45 percent, and most often used to promote flowering in ornamental plants.

superposed

Accessory buds which occur above the axillary buds.

supersaturation

The uptake of unusual amounts of water by a plant; this can cause plant specimens to mold rather than dry.

supersporangium

A structure containing tetrasporangia and acting as a sporangium.

supra-axillary

Borne above the axil.

suprabasal

Above the base, usually referring to pinnae or pinnules.

supramedial

Beyond the middle.

surculose

Producing suckers.

suspended

Describes an ovule that is hanging from the apex of the cell.

swale

A wet depression between beach ridges, fed by ground water and runoff, rarely influenced by changes in water level.

swell

A huge natural dome structure where movement of the earth's crust has raised stratigraphic layers in mounds rather than breaking them with a fault. Erosion exposes the oldest layers in the middle with subsequent layers surrounding it in concentric circles.

symbiosis (adj. symbiotic)

The living together of different species of organism which may or may not be to their mutual benefit. See also: mutualism, parasitism.

symmetrical

Describes a flower that can be divided into similar halves.

sympatric

Describes two or more closely-related species having coincident or overlapping ranges of distribution but not interbreeding. See also: allopatric.

sympodium (pl. sympodia, adj. sympodial)

A primary axis without a single, persistent growing point that develops from a series of lateral branches which change direction in succession and give it a zigzag form, as occurs with orchids of the genus Cattleya. See also: monopodium.

syncarp

An aggregate or multiple fruit produced from fused or coherent pistils, the small individual fruits massing and growing together into a single fruit, coalescent.

syncarpous

With the carpels of the gynoecium united in a compound ovary.

syncline

A geological structure that appears when strata fold downward toward a common line.

synoicous (alt. synaecious)

Having the male and the female organs mixed together in the same cluster.

synonym (abr. syn.)

Any one of two or more names used for the same taxon rank; a rejected name due to misapplication or difference in taxonomic judgment. See also: basionym, homonym, tautonym, autonym, taxonomic synonym, nomenclatural synonym.

syntype

Any one of two or more specimens cited by the author when no holotype was designated, or when two or more were designated. See also: holotype, lectotype, neotype, isotype, nomenclatural type, topotype.

systematics

The study of the evolutionary and genetic relationships among organisms and of their phenotype similarities and differences.

tautonym

An illegitimate binomial in which the genus and species are the same word, such as Amoracia armoracia, later changed to Armoracia rusticana. See also: basionym, homonym, synonym, autonym.

taxon (pl. taxa)

A group of genetically similar organisms that are classified together as a species, genus, family, etc.

taxonomic synonym

Any one of two or more different names based on different plant specimens which were later judged to belong to the same taxon.

taxonomy (adj. taxonomic)

The classification of organisms based on genetic similarities.

temperature summation

The totality of effective temperatures or day-degrees for a specified period of time, especially the time required for an organism to reach maturity, like a summer. See also: aliquote.

temporal

1. Refers to the sides of the skull behind the eyes, the temples. 2. Refers to time.

tender

Describes a plant easily killed by frost.

tendril

A clasping, twining, slender outgrowth of the stem that helps support climbing plants.

tension

The stress resulting from elongation.

tepal

A division of the perianth--a sepal or a petal--of a flower in which the calyx and corolla are almost identical in appearances, as occurs in tulips and lilies. In Orchidaceae, this term refers to any sepal or petal, except the labellum.

terete

Having a circular transverse section.

terminal

Apical.

ternate

With three nearly equal divisions.

terrace

The entire outdoor paved surface; the term often refers to the patio only.

terrarium

A small artificial environment for a specified habitat. An aquarium is for a water habitat, usually containing fish and plants. A terrarium generally has a woodland setting, with the emphasis on plants rather than animals.

terrestrial

Growing in soil.

tetraploid

Having twice the normal number of chromosomes.

thallus (pl. thalli)

In cryptogams, a cellular expansion taking the place of stem and foliage and forming the main body fungi and lichens.

thatch

A layer of dead grass that does not decay into soil.

thermal stratification

The successive horizontal layers of a body of water having different temperatures, each layer more or less sharply different from the adjoining ones, with the warmest at the top. See also: thermocline, epilimnion, turnover.

thermocline

In bodies of water, there are normally stratified layers of decreasing temperature with increased depth. Thermocline is the layer where the temperature starts to decrease rapidly, about one degree centigrade or more with each meter (3 feet) of depth. See also: epilimnion, thermal stratification.

thorn

A stout, sharp, woody outgrowth of the stem or branch.

throat

The orifice of a gamopetalous corolla or calyx; the part between the proper tube and the limb.

tier

A radial, layered branching habit of excurrent trees.

till

Mixed deposits of gravel, boulders, sand, and other materials that were carried by a glacier.

timber

Standing trees, felled trees, or seasoned logs. See also: lumber, pulpwood.

timber cruising (timber cruiser)

The process of surveying forest land with the objective of predicting how many board feet of lumber the plot will yield.

tip

The apex.

tip layering

A propagative method similar to air layering, except a flexible branch such as blackberry, Rubus, is bent to the ground and buried in moist soil or a mixture of peat moss and sand, instead of being wrapped on the upright stem.

tissue culture

The growth of small pieces of plant tissue (usually the meristem) under sterile conditions in artificial media.

tooth

1. The processes comprising the fringe around a peristome. 2. The smallest division of a frond.

toothed

Having the margin shallowly divided into small, tooth-like segments.

top variety

The variety bud-grafted to the understock, and thus the variety that flowers.

topography

The configuration of a surface including its relief and the position of its natural and man-made features.

topotype

A specimen collected later from the original type locality, or from the area from which the type was described. See also: holotype, lectotype, neotype, isotype, nomenclatural type, syntype.

torus

The receptacle of a flower.

trailing

Lying prostrate on the surface or on other vegetation.

translucent

Thin enough to transmit light, but not a concrete image.

transparent

Thin enough to transmit an image.

transpiration

The passage of water through a land plant and usually out the pores of its leaves.

transplant

To move a plant from one place to another.

transverse

Cross-wise in position.

tree

A woody, self-supporting perennial plant usually with a single main stem and generally growing more than 20 feet tall.

tree line (alt. tree limit, timberline)

The height above which trees can no longer survive on a mountainside, or the northern or southern limit beyond which only stunted forms appear on a continent toward a pole.

trench

A long cut, ditch, channel, especially man-made.

tri-

A prefix meaning three.

triangular

Having the outline of a triangle.

trimerous

Having flower parts, such as petals, sepals, and stamens, in groups of three.

tropical

Of, being, or characteristic of a region or climate that is frost-free with temperatures high enough to support year-round plant growth.

true leaf

A leaf typical of a plant that appears subsequent to the cotyledons.

trunk

The major woody stem of a tree.

tuber

A thickened and short subterranean branch having numerous buds or eyes and used for food storage.

tubercle

A small tuber or tuber-like (not necessarily subterranean) body.

tubular

With the petals partly united to form a tube.

tundra

The vegetation type of very cold climates overlying permafrost and consisting of lichens, sedges, mosses, grasses, and low woody plants.

turbinate

Top-shaped; inversely conical.

turnover (syn. overturn, syn. fall overturn)

The cycling of upper and lower strata of water in bodies of fresh water in autumn, and vice versa in spring, caused by the heating or cooling of upper surfaces. When the upper surface is cooler than the lower water, the cool water sinks.

twig

The end subdivision of a branch; a young shoot, generally applied to the growth of the past season.

twining

Clasping by winding around.

twisted

The seta of many mosses twists strongly in drying. If the twist is such as would be made by seizing the capsule and twisting it to the right, it is said to be twisted to the right. It is possible that this twisting of the seta aids in scattering the spores.

type

One of several categories of herbarium specimens, chosen by taxonomists as being close or identical to that chosen by the original author.

ultimate

Of the lowest order; the smallest division.

umbel

An inflorescence in which the peduncles or pedicels of a cluster spring from the same point.

umbellet

A secondary umbel.

underdrainage

1. The placement of perforated plastic pipe or porous clay pipe underground, often with a layer of crushed stone over it, to carry away excess water. 2. A natural or man-made system allowing excess water to be carried away from a cultivated field.

understock (syn. rhizome, syn. rootstock)

The stock or root plant onto which a shoot has been grafted to produce a new plant in bud-grafting, especially in cases of double-worked trees.

understory

The shrubs and smaller trees between the forest canopy and the ground cover.

undifferentiated

Describes parts or tissues which are very difficult to tell apart, like the tepals of tulips, Tulipa.

unicellular

Made of one cell.

uniform

Always having the same shape, as opposed to dimorphous.

union

A graft.

unisexual

A flower of one sex only, either pistillate (female) or staminate (male).

united

Fused together.

unstratified

Lacking distinct layers.

vacuole

A cavity or vesicle in the cytoplasm of a cell usually containing fluid.

vale

A small valley.

valve

One of the pieces into which a dehiscing capsule splits.

vane

One leaf of a windmill or pinwheel.

variegated

Marked, striped, or blotched with some color in addition to the plant's general overall color.

variety (alt. varietas, abr. var.)

The rank of taxa below subspecies but above forma; a plant which retains most of the characteristics of the species, but differs in some way such as flower or leaf color, size of mature plant, etc. A variety is added to the specific binomial and preceded by "var.", such as saxatilis in the epithet Juniperus communis var. saxatilis.

vascular

Furnished with vessels or ducts.

vegetational analysis

Any of various methods of studying small areas of constituent plants, often counting the numbers of plants of communities, to make extrapolations to a larger area. See also: belt transect, basal area, vegetational cover, timber cruising.

veil

The calyptra.

vein

The thread of fibro-vascular tissue in a leaf or other organ, especially those which branch (as distinguished from nerves).

veinlet

A subdivision or branch of a vein.

veld (alt. veldt)

A term commonly used in South Africa for open country occupied by grasslands in higher elevations and scrub or savanna at lower elevations.

venation (syn. nervation)

The manner in which the veins are arranged in the leaf.

ventral

Belonging to the anterior or inner face of an organ; the opposite of dorsal.

verge

Border, limit, or boundary; a berm.

vernal

Appearing in spring.

vernation

The arrangement of leaves in the bud.

very double

Roses with a great many petals.

vesicle

A small bladder or air-cavity.

vessel

A row of lignified water-conducting cells rendered continuous by the absorption of the crosswalls.

viable

Describes a seed that is capable of germinating.

vicariation

The occurrence of ecological equivalents replacing each other in similar habitats in different geographic areas, e.g., caribou in North America and reindeer in Eurasia.

vine

A plant that trails, clings, or twines, and requires support to grow vertically.

viscous

Not free-flowing; having the consistency of syrup.

vouchering

Furnishing proof, supporting a claim, as of taxonomic study.

Wardian case

A case of glass sides and top used to maintain the humidity necessary for growing tropical and subtropical plants in temperate region buildings. A popular feature of Victorian homes, used often to display ferns.

water sprout

A sucker produced on the trunk, stem, or large branch of a plant, particularly fruit trees, usually growing straight and at a right angle to the axis. These rapidly growing suckers are generally removed to allow a more open tree and to provide better nutrition to the fruit.

watershed

The complete area from which runoff drains to feed a stream or body of water.

wavy

See also: undulate.

weed

A plant growing where it is not wanted, often to the detriment of a crop or the disfigurement of a landscape design.

wetland

An area where saturation or repeated inundation of water is the determining factor in the nature of the soils, as well as the plants and animals living there. Included in the term are marshes, swamps, bogs, fens, bay heads, wet meadows, potholes, sloughs, bayous, river flood plains, estuaries, and lake margins.

whole

Having all its proper parts or components, often describing a flower.

whorl (adj. whorled)

An arrangement of leaves, petals, sepals, etc., in a circle around the stem.

wildfire

A fire that is out of control, such as a forest fire or a burn through a grassland, often threatening houses or farms.

wildflower

A flowering plant growing and usually propagating itself outside of cultivation. Often, but not always, refers to plants native to a region.

windward

The side from which the wind blows. See also: leeward.

wing

1. A thin, dry, leaf-like membrane found on many fruits, seeds, and leafstalks; any membranous or thin expansion bordering or surrounding an organ. 2. The lateral petal of a papilionaceous corolla.

winged

With projecting thin flat membranes or corky outgrowths.

wood

The hard, fibrous inner tissue of the trunk and branches of a tree or shrub.

woodland (syn. woods)

An area primarily covered with trees.

woody

Forming stems that mature to wood.

woody plant

With the stems and limbs containing lignin.

woolly

Clothed with long and tortuous or matted hairs.

xeric

Of, or adapted to, an extremely dry habitat.

xylem

Tissue specialized for the transport of water and minerals upward through the plant.

zygomorphic

Capable of division by only one plane of symmetry.

zygote

The diploid cell formed by the union of two gametes.