F1 The first filial generation, the first generation of a given mating; the first generation of a cross.

F2 The second filial generation obtained by self-fertilization or crossing inter se of F1 individuals.

F2 varieties The next generation seed derived from the hybrid (F1) generations; the variety cannot be perpetuated by growing additional generations. Examples: `Foremost F2' tomato, `Market Pride' cantaloupe, 'Violet Blue' petunia, `Seven-Eleven' pansy.

F3 The Progeny obtained by self-fertilizing or crossing inter se of F2 individuals.

Fabaceae n. The pea family.

fabiform adj. Kidney-bean shaped.

faceted (L. facies: face, aspect) adj. With many plane surfaces, like a cut gem, as in some seeds.

facial (L. facies: face) adj. Pertaining to or on the face, rather than the sides or edges

faciation n. A subdivision of an association characterized by a particular group of dominant species and determined by minor climatic differences. A part of a climax association which lacks some of the dominants of the normal association due to slight differences in environmental fundamentals.

facies (L. facies: face, aspect) n. Sum total of features that reflect the specific environmental conditions under which a given rock was formed or deposited. The features may be lithologic, sedimentological, or faunal. In a sedimentary facies, mineral composition, sedimentary structures, and bedding characteristics are all diagnostic of a specific rock or lithofacies.

factor n. A synonym for gene; same as gene.

facultative adj. Capable of functioning under varying environmental conditions, e.g. a parasite which can survive with or without a host, a plant that can live a parasitic or nonparasitic life. Cf. obligate.

Fagaceae n. The oak family.

falcate (L. falcatus: sickle-shaped) adj. Curved like a sickle; hooked; shaped like the beak of a falcon; curved with parallel edges. Syn. falciform, acinaciform.

falcarinone n. A type of polyacetylene.

falciform (L. falx, falcis: sickle) See falcate.

falls n. The sepals of an Iris

false annual ring An extra growth ring produced in a season with a drought and then more rain.

family n. A group of one to many genera believed to be related phylogenetically, usually clearly separable from other such groups. The taxonomic category above genus and below order.

fan-compound adj. A compound leaf in which leaflets are arranged in the shape of a fan; a compound leaf with leaflets radiating from a single point; a palmate-compound leaf.

fangy adj. froked, fang-like.

fan-lobed adj. With major lobes radiating from a single point; palmate-lobed.

fan-veined adj. With main veins radiating from a single point; palmate-veined.

farina (L. farina: flour, powder) n. A waxy-appearing substance exuded from glands. Pollen.

farinaceous (L. farina: flour, powder) adj. Containing flour; starchy; mealy, resembling flour.

farinose (L. farina: flour, powder) adj. Full of meal; mealy; covered with a white, powdery substance.

fascia (L. fascia: band, strip) n. (pl. fasciae) A distinctly marked band of color.

fasciarate (L. fascia: band, strip) adj. Band-shaped; long and narrow with untapering margins, with a length to breadth ratio of 12 to 1.

fasciate See fasciated.

fasciated (L. fascis: bundle) adj. Compressed into a bundle or band; grown closely together; with the stems malformed and flattened as if several separate stems had been fused together. Syn. fasciate.

fasciately adv. See fasciated.

fasciation (L. fascis: bundle) n. The process of becoming fasciate. An abnormal flattening or coalescence of stems or leaf stalks.

fascicle (L. fasciculus: small bundle) n. A small bundle or tuft, as of fibers, leaves, flowers, etc., as of pine needles, as the branches in Sphagnum. See also vascular bundle.

fascicled adj. See fascicle.

fascicular (L. fasciculus: small bundle) adj. Pertaining to or forming a fascicle; fasciculate.

fascicular cambium A lateral meristem developing from undifferentiated procambium in a vascular bundle, with the interfascicular cambium making up the vascular cambium.

fasciculate (L. fasciculus: small bundle) adj. Of branching or growth form, many branches arising from one point like a bundle of sticks; of rhizines, many simple rhizines arising from one point or region. Bunched together, arranged in fascicles, e.g. the branches of Sphagnum.

fasciculated See fasciculate.

fasciculated root A fibrous root is which some of the fibres or branches are thickened.

fasciculately adv. See fasciculate.

fastigiate (L. fastigium: roof with two slopes) adj. Having a conical or tapering outline; having parallel upright branches; having branches close to stem and erect, giving a broom-like appearance.

fats and oils Lipids formed by the combination of glycerol with fatty acids. Fats occur widely in animals and plants as an energy store and insulating material. Vegetable fats and oils are used in making soaps, margarines, cooking oils, paints, and lubricants. Animal fats are used in foods, soaps, and candles. Oils are distinguished from fats by being liquid at 20°C, whereas fats are solid. Mineral oils are hydrocarbons rather than lipids (see oil).

fatty acid An organic acid that comprises one or more carboxyl groups (-COOH) attached to an alkyl group. Fatty acids combine with glycerol to form glycerides, the main constituents of fats and oils. Animal fats tend to be hard because they contain a high proportion of saturated fatty acids; soft fats, such as vegetable and fish oils, contain more unsaturated and polyunsaturated fatty acids (containing one or more double bonds). The risk of heart disease associated with dietary fat is probably reduced if the fat consumed is rich in polyunsaturated fatty acids. However, the consumption of trans-fatty acids has been associated with an increased risk of heart disease. Trans-fatty acids are a form of polyunsaturates produced by hydrogenation, the process used to harden vegetable and fish oils in the manufacture of margarine. Certain essential fatty acids are normally required in small amounts in the diet.

fatty acids See fatty acid.

faucal (L. fauces: throat) adj. Of or pertaining to the throat of a calyx or corolla. Syn. faucial

fauces (L. fauces: throat) n. The throat of a calyx or corolla.

faucial (L. fauces, faucium: throat) See faucal.

faveolate (L. favus: honeycomb) adj. Honeycombed or pitted; alveolate. Syn. favose.

favose See faveolate.

favulariate adj. Of a surface, finely ribbed, the ribs separated by zig-zag furrows.

feather-compound adj. With the midribs of main leaflets branching from a central midrib at several points in a featherlike pattern; pinnate-compound.

feather-lobed adj. With the main lobes more or less at right angles to the midrib, not radiating from a central point; pinnate-lobed.

feather-veined adj. Said of leaves whose veins all arise pinnately from a single midrib.

febrifuge n., adj. A medication that reduces fever; an antipyretic. Acting to reduce fever.

federal seed act The federal seed act of 1938 as amended and regulated (1976), the U.S statute governing aspects of seed production, handling, and sales.

Federal Seed Act See federal seed act.

feeder root One of the numerous small roots of a plant, through which moisture and nutrients are absorbed from the soil.

female gamete In flowering plants, a cell at the apex of the embryo sac immediately adjacent to the micropyle and associated with the synergid cells.

female gametophyte In flowering plants, a haploid organism usually made up of antipodals, egg cell, polar nuclei, synergids.

fen n. Low land covered wholly or partially with water but producing sedge, coarse grasses, or other aquatic plants; boggy land; a moor or marsh; plant community on alkaline, neutral, or slightly acid peat.

fenestra (L. fenestra: window, opening) n. (pl. fenestrae). A window-like perforation, opening, or translucent area.

fenestrae See fenestra.

fenestrate See fenestrated.

fenestrated (L. fenestra: window, hole, opening) adj. With open areas or slits. A type of leaf anatomy with small perforation or transparent spots, e.g. the uni-fenestrated and pluri-fenestrated patterns of thickenings of the inner capsule wall cells in various liverworts (e.g. Lejeuneaceae); also used to describe some types of perforated peristome teeth in mosses.

fenestration (L. fenestra: window, hole, opening) n. The pattern of translucent spots that occurs on and around the lids of certain pitcherplants of the genera Cephalotus and Sarracenia.

feral adj. Of animals and plants existing in a wild or uncultivated state, esp. after being domestic or cultivated.

fern n. Herbs with broad but highly dissected leaves and no flowers. A leafy plant of the phylum Filicinophyta (or, in traditional classifications, the class Filicinae - See pteridophyte) spread by spores, not seeds. Like mosses and liverworts, clubmosses and horsetails, ferns grow in two physically distinct forms that alternate during their life cycle. For the main part of this cycle, a fern consists of a short stem (rhizome) from which roots grow down into the soil, and leafy fronds grow upwards. This is called the sporophyte generation because it produces spores inside spore cases on the underside or margins of the fronds. These spore cases open and scatter the spores which, when they fall on moist soil, germinate to produce heart-shaped plants 2 to 3 cm (about an inch) across, called prothalli. These bear the sex organs, which in ferns are cavities containing microscopic egg cells and sperms. The sperms swim to fertilize the egg when the prothallus is wet, so ferns are able to reproduce sexually only in damp habitats. After fertilization the egg cell develops into a new sporophyte plant. Some ferns reproduce asexually by leaf buds or, in the case of bracken, by rhizomes. Many fossil ferns are known, some of which, unlike modern ferns, had seeds. About 9,000 species of living fern are known. The species Ophioglossum, known as adder's tongue, has the highest known chromosome number of any plant (over 1,000). This indicates an ancient lineage. Common temperate species include lady fern, Anthyrium filix-femina, male fern, D. filix-mas, polypody, and bracken, Pteridium aquilinum. A non-flowering, vascular plant of the class Polypodiopsida.

fern allies See fern ally.

fern ally A non-flowering, vascular plant belonging to one of the following classes: Equisetopsida (horsetails,) Lycopdiopsida (club-mosses, spike-mosses and quillworts,) and Rhyniopsida (whisk-fern).

ferruginous (L. ferrugo, ferruginis: rust, rust-colored) adj. Reddish-brown; rust-coloured.

fertile (L. fertilis: fertile, productive) adj. Capable of engaging in the process of fertilisation; capable of bearing seeds; capable of bearing pollen; capable of bearing spores.

fertility n. The reproductive capacity of an organism. Cf. fecundity. The property of soil that allows it to provide available nutrients and moisture to plants.

fertilisation See fertilization.

fertilization (L. fertilis: fruitful, productive) n. The union of male and female gametes (reproductive cells) during the process of sexual reproduction to form a zygote. It involves the fusion of the gametic nuclei (karyogamy) and cytoplasm (plasmogamy). As each gamete contains only half the correct number of chromosomes, fertilization and zygote formation results in a cell with the full complement of chromosomes, half of which are derived from each of the parents. In animals the process involves fusion of the nuclei of a spermatozoan and an ovum. In most aquatic animals (e.g. fish) this takes place in the surrounding water, into which the gametes are shed. Among most terrestrial animals (e.g. insects, many mammals) fertilization occurs in the body of the female, into which the sperms are introduced. In flowering plants, after pollination, the grain pollen produces a pollen tube, which grows down into the female reproductive organ (carpel) to enable a male gamete nucleus to fuse with the egg nucleus (see double fertilization). In self-fertilization the male and female gametes are derived from the same individual. Among plants, self-fertilization (also called autogamy) is common in many cultivated species, e.g. wheat and oats. However, self-fertilization is a form of inbreeding and does not allow for the mixing of genetic material; if it occurs over a number of generations it will result in offspring being less vigorous and productive than those resulting from cross-fertilization. In cross-fertilization (also called allogamy in plants) the gametes are derived from different individuals. In plants the pollen comes either from another flower of the same plant or from a different plant (see also incompatibility).

ferulic acid An acid derived from cinnamic acid.

festucoid (L. festuca: wisp of straw; Gr. eidô: to look like) adj. Resembling the grass Festuca; a member of the Festucoideae group of grasses.

fetid (L. fetidus: stinking) adj. With an offensive odor; stinking.

fetor n. An offensive odor; a stench.

fiber n. See fibre.

fiber tracheid A fiber with thick walls and pointed ends that has simple pits and is found in wood tissue.

Fibonacci series A series of naumbers formed by the addition of the last two numbers, i.e. 1, 2, 3, 5, 8, 13, 21, ... used to describe the spirals of parts in phyllotactic series.

fibre (L. fibra: fibre, filament) n. An elongated plant cell whose walls are extensively (usually completely) thickened with lignin (see sclerenchyma). Fibres are found in the vascular tissue, usually in the xylem, where they provide structural support. The term is often used loosely to mean any kind of xylem element. The fibres of many species, e.g. flax, are of commercial importance. Syn. fiber.

fibril (L. fibra: fibre, filament) n. A delicate fiber or hair; a small fibre; a subdivision of a fibre. Syn. fibrilla.

fibrilla n. (pl. fibrillae) See fibril.

fibrillae See fibrilla.

fibrillar (L. fibra: fibre, filament) adj. Of, pertaining to, or of the nature of fibrils.

fibrillary adv. See fibrillar.

fibrillate See fibrillose.

fibrilose (L. fibra: fibre, filament) adj. Bearing fibrils; with fine, fiber-like wall thickenings (fibrils); e.g. the Sphagnum hyalocysts where the fibrils may be spiral or annular; covered with hairlike appendages, as the under surface of some lichens; composed of little strings or fibers.

fibrous (L. fibra: fibre, filament) adj. 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. A root system with all of the branches of approximately equal thickness, as in the grasses and many other monocots.

fibrovascular n. Containing woody fiber and ducts, as the stems of all flowering plants' and ferns; opposed to cellular. See vascular bundle. fid (L. findere: to split) suffix. Meaning divided, lobed; divided, lobed but only narrowly joined in relation to the size of the segments; e.g. 2-fid, bifid, 3-fid.

fiddlehead n. One of the young unfurling fronds of some ferns that are often eaten as greens.

filament (L. filum: thread) n. A thread-like structure. The stalk of a stamen which supports the anther; a thread one or more cells thick; in blue-green Algae, a trichome enclosed in a mucilaginous sheath. Cf. anther.

filamentary (L. filamentum: covering of threads) adj. pertaining to or of the nature of a filament or filaments.

filamentose See filamentous.

filamentous (L. filamentum: covering of threads) adj. Bearing or resembling filaments; composed or containing filaments; pertianing to filaments. Also. filamentose.

filantherous (L. filum: thread; Gr. anthęros: flowered) adj. Of a stamen with a distinct anther and filament.

filial generation In hybrid offspring, the first cross is designated as F1, the second cross as F2, etc.

filical (L. filix, filicis: fern) adj. Of or pertaining to ferns; filicoid.

Filicinophyta (L. filix, filicis: fern; Gr. phyton: plant) n. A phylum of mainly terrestrial vascular plants (see tracheophyte) - the ferns. Ferns are perennial plants bearing large conspicuous leaves (fronds: see megaphyll) usually arising from either a rhizome or a short erect stem. Bracken is a common example. Only the tree ferns have stems that reach an appreciable height. There is a characteristic uncurling of the young leaves as they expand into the adult form. Reproduction is by means of spores borne on the underside of specialized leaves (sporophylls). Syn. Pterophyta.

filicoid (L. filix, filicis: fern; eidô: to look lik) adj. Fern-Iike in appearance.

filiferous adj. Bearing filaments or filament like growths.

filiform (L. filum. fili: thread; forma: shape) adj. Thread-like, long and very slender; filamentous; coarser than capilliform.

filmy fern A fern of shady places with exceptionally thin frond leaflets, usually of the family Hymenophyllaceae.

fimbria (L. fimbria: fringes) n. (pl. fimbriae) A fringe or fringe border or fringelike process.

fimbriae See fimbria.

fimbrial adj. Pertaining to or having a fringe. Said of leaf venation, high order veins joining and forming a continuous vein running just inside the margin of the blade.

fimbriate (L. fimbriatus: fringed) adj. Cut into regular segments and appearing fringed at the margins, usually with hairs or hair-like structures (fimbrillae) along the margin; fringed, generally with radiating cell walls of partly eroded marginal cells; e.g. the stem leaf apices of Sphagnum fimbriatum. Cf. laciniate.

fimbriation (L. fimbriatus: fringed) n. A fringe or fringelike part; fimbriate or fringed condition.

fimbrilla (diminutive of L. fimbria: fringes) n. (pl. fimbrillae) A single unit of marginal fringe.

fimbrillae See fimbrilla.

fimbrillate (diminutive of L. fimbria: fringes) adj. Fringed with very fine hairs. Syn. fimbriolate.

fimbriolate See fimbrillate.

fimicolous adj. Growing on dung heaps.

firn n. Rounded, well-bonded snow that is older than one year; also called névé.

first-generation synthetic varieties The first-generation progenies derived by intercrossing a specific set of clones or seed-propagated lines; these may include varieties of normally cross-fertilizing or self-fertilizing crops into which mechanisms have been introduced to maximize cross-fertilization such as male sterility or self-incompatibility. These varieties usually contain mixtures of seed that result from cross-fertilization, self-fertilization and sib-fertilization; the variety consists of only the first-generation progenies after intercrossing and cannot be reproduced from seed of the first generation. Examples: `Gahi' pearl millet, `Vitagraze' rye, `Tempo' alfalfa.

fission (L. fissus: split, divided) n. A type of asexual reproduction occurring in some unicellular organisms, e.g. diatoms, protozoans, and bacteria, in which the parent cell divides to form two (binary fission) or more (multiple fission) similar daughter cells.

fissitunicate adj. In lichens, said of a type of bitunicate ascus discharge where the outer wall ruptures at the apex and slips down towards the base, and the inner wall swells.

fissura n. (pl. fissurae) A sharp, straight split that appears during germination in certain inaperturate pollen grains. Examples: Taxodium (Taxodiaceae), Cupressus (Cupressaceae).

fissurae See fissura.

fissured adj. Cracked, split.

fistula (L. fissura: crack, fissure, cleft) (L. fistula: pipe) n. Pathological or artifical pipe-like opening; water-conducting vessel.

fistular (L. fistula: pipe) adj. Hollow throughout its length.

fistulose adj. See fistulous.

fistulous (L. fistula: pipe) adj. Cylindrical or terete, hollow and fully enclosed, capped at both ends. Having the form or nature of a fistula. Syn. fistulose.

flabellate (L. flabellum: fan) adj. Fan-shaped; dilated in a wedge-shape.

flabelliform (L. flabellum: fan; forma: shape) See flabellate.

flaccid (L. flaccidus: flabby) adj. Weak, limp, soft, or flabby; not rigid; leaves that do not have enough water and are about to wilt or are wilting. Cf. turgid.

flag n. An other name for a in a papilionoid flower also know as the standard.

flagella See flagellum.

flagellate (L. flagellum: whip) adj. n. With long, slender runners; producing filiform runners or runnerlike branches, as the strawberry. A protozoan organism that moves using long, whip-like appendages called flagella. Some move freely but make their own food using photosynthesis; some prey on other organisms; and some are parasites or symbionts. In fact the group has little in common except flagella. They are often divided into plant-like species (phytoflagellates) and animal-like species (zooflagellates).

flagellated (L. flagellum: whip) adj. With a flagellum or flagella. See flagellum.

flagellates (L. flagellum: whip) n. Cells with flagella but no cell-wall.

flagelliflorous (L. flagellum: whip; florus: flowered) adj. Bearing flowers at the ends of long, pendulous branches.

flagelliform (L. flagellum: whip; forma: shape) adj. Elongate and slender; whip-like; most often referring to roots or stems, or as branches with a gradual attenuation from ordinary leaves at the branch base to vestigial-leaved branch tips; e.g. Isothecium stoloniferum.

flagellin n. Protein which is the primary component of prokaryotic flagella.

flagellum (L. flagellum: whip) n. (pl. flagella) Any of various elongated filiform appendages of plants or animals: as the slender distal part of an antenna or a long tapering process that projects singly or in groups from a cell and is the primary organ of motion of many microorganisms. A tiny whiplike appendage, capable of movement. In prokaryotes: a long slender threadlike structure that protrudes from the cell surface of a bacterium. It rotates from its base and propels the bacterium along; up to several micrometres in length, a flagellum is constructed of numerous subunits of the protein flagellin flange, n. See also: undulipodium.

flaky adj. Of bark with loose scales which are easily rubbed off.

flange n. A projecting rim or edge.

flavanone n. A flavonoid isomeric with a chalcone, differing from flavones in lacking the double-bond in the 2,3-position, usually colorless or slightly yellow.

flavedo (L. flavus: yellow) n. The coloured outer peel layer of citrus fruits, also called the epicarp or zest. It contains the oil sacs, and hence the aromatic oils, and numerous plastids which are green and contain chlorophyll in the unripe fruit, turning yellow or orange in the ripe fruit, when they contain carotene and xanthophyll.

flavescent (L. flavus: yellow) adj. Yellowish.

flavic (L. flavus: yellow) adj. Yellowish, yellow. Syn. flavicant.

flavicant See flavic.

flavid (L. flavus: yellow) adj. Golden yellow.

flavone See flavones.

flavones n. A flavonoid that lack the 3-hydroxy group of flavonols, derived from flavanones by oxidation, yellow in color

flavonoid adj. n. One of a group of usually coloured compounds consisting of two six-carbon rings joined by a three-carbon link. They are important compounds in plants where they produce the pigmentation of flowers and leaves. The anthocyanins are one group that typically produce purple colours (as in red cabbage).

flavonoid sulphate A flavonoid esterified with sulfate groups, mono- to tetrasulfate esters of common flavones and flavonols or their methyl ethers.

flavoroid n. A category of antioxidant compounds.

fleabane n. Any of various plants of the genus Erigeron, having variously colored, many-rayed, daisylike flower heads.

fleshy adj. Thick and pulpy, asa a fruit; succulent; thick and tender, as a leaf.

flexible adj. Easily bent or twisted.

flexuose See flexuous.

flexuosely adv. See flexuose

flexuoseness n. See flexuose.

flexuous (L. flexus: curve) adj. Bent from side to side in a zig-zag form. With curves or bends; sinuous; somewhat zigzagged. Syn. flexuose.

flexuously adv. See flexuous.

flexuousness n. See flexuous.

floating-leaved plants Plants with leaves on the water surface, rooted or non-rooted.

floc n. A tuft of soft, woolly hair.

floccose (L. floccus: flock of wool) adj. Said of pubescence which gives the impression of irregular tufts of cotton or wool, which tend to rub off and adhere in small masses. Bearing tufts of long, soft, tangled hairs.

flocculence n. See flocculent.

flocculent (L. flocculus: little flock) adj. Bearing tufts of very fine woolly hairs; like or in tufts of wool etc.; downy; floccose. Syn. flocculose.

flocculose See flocculent.

floccus (L. floccus: flock of wool) n. (pl. flocci). A tuft of woolly, tangled hairs.

flora (L. flos, floris: flower) n. (pl. floras, florae) The plants of a particular region or period, listed by species and considered as a whole; a work systematically describing such plants; plants as distinguished from fauna.

floral (L. florus: flowered) adj. Belonging to or associated with a flower.

floral cup A cup-shaped or tubular part of a flower.

floral diagram A stylised plan diagram of a flower showing its general orientation and the number and relationships (aestivation, connation, adnation, etc.) of its parts.

floral envelope A collective term for the calyx and corolla; the calyx in a flower lacking a corolla, i.e. the perianth.

floral formula A formula showing the number and some of the relationships (connation, adnation, etc.) of the parts of a flower; some information about the fruit can also be incorporated.

floral region An area with a degree of homogeneity of species existing because of similarities in topography, climate, etc., in the region. Also floristic region, floristic area.

floral tube An elongated tubular portion of a perianth

florescence (L. florescere: to begin to flower) n. The flowering period; bursting into bloom; the process, state, or time of floweringl alternatively: anthesis.

floret (diminutive de L. flos, floris: flower) n. Each of the small flowers making up a composite flower-head; each of the flowering stems making up a head of cauliflower, broccoli, etc.; a small flower, as a grass flower in a spikelet, or a flower of the Compositae (Asteraceae) in an involucrate head.

floricane (L. flos, floris: flower; canna: stick, cane, rush) n. The second year flowering and fruiting cane (shoot) of a biennal plant, especially of a bramble (Rubus). Cf. primocane.

florid (L. floridus: flowered) adj. Covered with flowers.

floridiness n. See florid.

floridity n. See florid.

floridly n. See florid.

floriferous (L. flos, floris: flower; ferre: to carry) adj. Flower-bearing.

florigen n. A plant hormone which appears to be produced in the leaves, then translocated to apical meristems where it initiates the formation of flowers.

florigenic adj. See florigen.

floristic area See floral region.

floristic region See floral region.

florulent (L. florulentus: spangled with flowers) adj. Flowery; blossoming.

floscule (L. floscula: little flower) n. A small flower; a floret.

flosculous (L. floscula: little flower) adj. Consisting of many gamopetalous florets.

flower n. The reproductive portion of the plant, consisting of stamens, pistils, or both, and usually including a perianth of sepals or both sepals and petals. The part of a plant containing or consisting of the organs of reproduction, either together in a monoclinous flower or separate in male and female flowers. The structure in angiosperms (flowering plants) that bears the organs for sexual reproduction. Flowers are very variable in form, ranging from the small green insignificant wind-pollinated flowers of many grasses to spectacular brightly coloured insect-pollinated flowers. Flowers are often grouped together into inflorescences, some of which (e.g. that of dandelion) are so compacted as to resemble a single flower. Typically flowers consist of a receptacle that bears sepals, petals, stamens, and carpels. The flower parts are adapted to bring about pollination and fertilization resulting in the formation of seeds and fruits. The sepals are usually green and leaflike and protect the flower bud. The petals of insect-pollinated flowers are adapted in many ingenious ways to attract insects and, in some instances, other animals. For example, some flowers are adapted to attract short-tongued insects by having an open shallow corolla tube and nectar situated in an exposed position. Flowers adapted for pollination by long-tongued insects have a long corolla tube of fused petals with nectar in a concealed position. The tongue of the insect brushes against the anthers and stigma before reaching the nectar. Wind-pollinated flowers, in contrast, are inconspicuous. The anthers dangle outside the corolla and the stigmas have a feathery surface to catch the pollen grains. Some species are adapted for self-pollination and have small flowers, no nectar, and stamens and carpels that mature simultaneously.

flower head A group of florets. See capitulum.

flowerhead See flower head.

fluted adj. With furrows or grooves. Of something long and slender.

foliaceous (L. foliaceus: in the shape of a leaf, foliated) adj. Having the form or texture of a foliage leaf; thin and leaf-like; bearing leaves. Leaf-like in color and texture; of or pertaining to leaves.

foliage (L. folia: leaf) n. The leaves of a plant, collectively.

foliar (L. folia: leaf) adj. Of, pertaining to, or having the nature of a leaf or leaves; leaf-like.

foliate (L. foliatus: stocked with leaves) adj. Having leaves; covered with leaves; leaf-like.

foliated (L. folia: leaf) adj. Leaf-shaped.

foliation (L. folia: leaf) n. The act of producing leaves; the arrangement of leaves within a bud; foliage.

foliature (L. foliatura: leafing, foliage) n. A leaf cluster; foliage.

folic acid A member of the B vitamin complex, found mostly in the leaves of plants. Also pteroylglutamic acid.

foliolate (L. foliolum: little leaf) adj. Pertaining to or having leaflets; usually used in compounds, such as bifoliolate or trifoliolate.

foliole (L. foliolum: little leaf) n. A leaflet, as of a compund leaf; a small, dorsiventral, leaf like organ or appendage.

foliolose (L. foliolum: little leaf) adj. With little leaves.

foliose (L. folium: leaf) adj. Leafy or leaf-like; closely covered with leaves.

follicle (L. folliculus: small bag) n. A dry dehiscent fruit that, when ripe, splits along (dehisces) one side to release its seeds. It is formed from a single carpel containing one or more seeds. Follicles do not occur singly but are grouped to form clusters (etaerios). Examples include larkspur, columbine, milkweed and monk's hood.

follicular (L. folliculus: small bag) adj. Of or pertaining to a follicle.

food chain The transfer of energy from green plants (the primary producers) through a sequence of organisms in which each eats the one below it in the chain and is eaten by the one above. Thus plants are eaten by herbivores, which are then eaten by carnivores. These may in turn be eaten by different carnivores. The position an organism occupies in a food chain is known as its trophic level. In practice, many animals feed at several different trophic levels, resulting in a more complex set of feeding relationships known as a food web.

foramen n. A narrow cavity.

forb (Gr. phorbę: food) n. A broad-leaved herb, a non-woody plant other than a grass, sedge, rush, etc., i.e. that is not a grass or grasslike. Cf. herb.

forcipate (L. forceps, forcipis: pliers) adj. Forceps-shaped; curved inward like nippers.

forest n. A dense growth of trees and underbrush covering a large tract.

forest fragmentation The continuing splitting of large forested areas by highways and residences which changes the habitat, therefore effects the acclimation and persistence of wildlife and indigenous plant species.

forked (L. furca: fork) adj. Divided into two or more essentially equal branches.

form (L. forma: shape) n. A small but constant variation within a population of plants, such as a white-flowered plant in a normally purple-flowered population. A category ranking below a subspecies, used chiefly for certain minor variations (e.g. the yellow passion fruit, Passiflora edulis flavicarpa, whose fruit is yellow rather than purple as in P. edulis proper); a sporadic variant, equivalent to `variety' of some botanists but generally trivial such as corolla or fruit color or habit response.

form taxon Binomial name (genus and species) given to a fossilized plant organ when it is found in isolation, i.e. when the taxonomic affinities of the organ are not known with certainty; for example spore and pollen taxa have their own binomial names, since it is rarley known which fossil genus may have produced them.

forma n. 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 of Cornus florida f. rubra.

formation n. One of the earth's largest subdivisions of vegetation types, usually of huge geographical extent and composed of communities that are similar in physiognomy and broad environmental description, such as the coniferous forests of Canada. Cf. climax, biome.

formenkreis (German for ring of forms) n. A series of related forms pinpointed geographically that originated entirely or primarily by geographic isolation. Cf. speciation, evolution.

formic acid A colorless caustic fuming liquid used in dyeing and finishing textiles and paper and in the manufacture of fumigants, insecticides, and refrigerants.

formula n. (pl. -las or formulae) A prescription of ingredients in fixed proportion; a recipe.

formulae See formula.

fornical adj. See fornix.

fornicate (L. fornicatus: vaulted, arched) adj. Arched, as in the arched scales (fornices) in the corolla throat of many members of the Boraginaceae.

fornices See fornix.

fornix (L. fornix: arch, vault) n. (pl. fornices) One of a set of small crests or scales in the throat of a corolla, as in many of the Boraginaceae.

fossil (L. fossilis: dug out) n. Generally, anything ancient, especially if it is discovered buried below ground (e.g. fossil fuel, fossil soil). The remains of a once-living organism, generally taken to be one that lived prior to the end of the last glacial period, i.e. fossils are older than 10 000 years. The term includes skeletons, tracks, impressions, trails, borings and casts. Fossils are usually found in consolidated rock, but not always (e.g. woolly mammoths living 20 000 years ago were recovered from the frozen tundra of Siberia). In its original sense, fossil meant anything dug up from the earth, including ores, precious stones, etc. The modern use of the word dates from the late 17th century. See also living fossil; and trace fossil.

fossiliferous (L. fossilis: dug out; ferre: to carry) adj. Bearing or containing fossils, as rocks or strata.

fossilise v. See fossilize.

fossilization (L. fossilis: dug out) n. The process by which a fossil is formed. It is unusual for organisms to be preserved complete and unaltered; generally, the soft parts decay and the hard parts undergo various degrees of change. solution and other chemical action may reduce the tissues to a thin film of carbon; this process is called 'carbonization'. The organism may be flattened by the compaction of sediments to form compressions. Porous structures, e.g. bones and shells, may be made more dense by the deposition of mineral matter by groundwater; this process is called 'permineralization' or 'petrifaction'. The internal physical structures of some shells may be changed as a result of solution and reprecipitation; in this process ('recrystallization') the original structure may be blurred or lost. Many shells which were originally composed of aragonite are recrystallized into the more stable mineral calcite. The solution of an original shell and the simultaneous deposition of another mineral material constitutes 'replacement'; this may occur molecule by molecule, in which case the microstructure is preserved, or en masse, where it is not. Common replacement minerals include silica or iron sulphide, but there are many others. The impression of skeletal remains in surrounding sediments constitutes a 'mould'. Where the external structures are preserved it is called an 'external mould' and where the internal features are preserved it is called an 'internal mould' or 'steinkern'. Filling of a mould cavity by mineral matter may produce a 'natural cast'. Tracks, trails, burrows, and other evidence of organic activity may also be preserved. These are called 'ichnofossils' or trace fossils.

fossilize (L. fossilis: dug out) v. To convert into fossils, i.e. replace organic substances with minerals, in the remains of an organism.

foundation seed A class of certified seed that is the progeny of breeder or foundation seed and is produced and handled under procedures established by the certifying agency for the purpose of maintaining genetic purity and identity. Seed stock produced from breeder seed by or under the direct control of an agricultural experiment station. Foundation seed is the source of certified seed, either directly or through registered seed.

foundation single cross A single cross in the production of a double, three-way, or top cross.

founder effect Genetic differences in a colonizing population during its establishment phase based on a small number of founders, unrelated to any selection effect. See also founder principle.

founder principle The situation in which a founding population does not represent a random sample of the original population; a form of sampling error. 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.

fovea (L. fovea: hole) n. (pl. foveae) A small pit or depression, e.g. some spores of Bruchia.

foveae See fovea.

foveate (L. fovea: hole) adj. With foveae; pitted

foveola (diminutive form L. fovea: hole) n. (pl. foveolae) A little fovea; a very small pit or depression. Syn. foveole, foveolet.

foveolae See foveola.

foveolar adj. See foveola.

foveolate adj. Honeycombed; minutely pitted; with foveolae. See foveola.

foveole See foveola.

foveolet See foveola.

fox fire Phosphorescent light caused by a fungus on decaying wood.

fractiflex A broken or intermittent zigzag line.

fragmentation n. Breaking up; a method of vegetative reproduction in which all or part of an organism is separated into parts capable of producing a new organism; fragmentation is found in various thalloid liverworts.

free adj. Not fused or united (with other organs).

free-central adj. A placentation in which the ovules are borne on a free-standing central placenta within the ovary.

free placentation See apocarpy.

free surface The exposed surface of an apical cell that is not surrounded by cell segments; that surface not in contact with other cells.

friable adj. Readily powdered, crumbling.

fringed adj. With hairs or bristles along the margin; with a border or edge decorated of hanging threads or strips. Cf. fimbriate.

frond (L. frons, frondis: leaves, foliage) n. A leaf, especially of fern or palm; a leaf-like expansion; a leaf-like portion of a non-vascular plant (e.g. a foliose alga); the leaf of ferns and some other cryptogams, usually having many divisions; the branched or foliose part of an erect stem, including branches, of a dendroid or frondose moss and some thalloid liverworts; properly the word frond includes both stipe and blade, but frequently it is used simply to designate any fernlike or featherlike foliage.

frondose (L. frons, frondis: leaves, foliage) adj. Leafy, frond-like, resembling a fern frond; in mosses: closely and regularly branched in one plane (pinnate), e.g. Thuidium; in liverworts: a thallus that is crisped or lobed.

fructan n. A polysaccharide derived from fructose, e.g. inulin.

fructescence (L. fructus: fruit) n. The fruiting period; the maturing or ripening of fruit.

fructiferous (L. fructifer: fruit bearing) adj. Fruit-bearing.

fructification (L. fructificatio, fructificationis: fructification) n. The fruiting process of a plant; the fruit of a plant. The producing of fruit. A seed-bearing or spore-bearing structure.

fructose n. A hexose sugar forming a 5-membered ring.

fruit (L. fructus: fruit) n. Technically a ripened ovary with its adnate parts, the seed-containing unit characteristic of all Angiosperms; the mature ovary of a seed plant. The structure formed from the ovary of a flower, usually after the ovules have been fertilized (see also parthenocarpy). It consists of the fruit wall (see pericarp) enclosing the seed(s). Other parts of the flower, such as the receptacle, may develop and contribute to the structure, resulting in a false fruit (see pseudocarp). The fruit may retain the seeds and be dispersed whole (an indehiscent fruit), or it may open (dehisce) to release the seeds (a dehiscent fruit). Fruits are divided into two main groups depending on whether the ovary wall remains dry or becomes fleshy (succulent). Succulent fruits are generally dispersed by animals and dry fruits by wind, water, or by some mechanical means. See also composite fruit.

fruit cycle The period, or length of time, between fruit set and maturity.

fruit-dot n. A sorus.

fruiting cycle The shortest period between successive generations of a plant; i.e. from propagule to fruit maturity (differs from breeding cycle in that the former may be reproduced vegetatively rather than from seed). Also fruiting rotation

fruiting rotation See fruiting cycle.

fruitlet n. Strictly speaking, a seed-bearing structure derived from a single free carel.

frutescent (L. frutex, fruticis: shrub) adj. Shrubby or becoming shrubby. Syn. frutical. Also fruticose.

frutex (L. frutex, fruticis: shrub) n. (pl. frutices) A shrub; a woody-stemmed plant smaller than a tree.

frutical See frutescent.

frutices See frutex.

fruticeta n. A vegetation type made up of scrubby forest.

fruticose (L. fruticosus: full of shrubs) Shrub-like, bushy, with many stems rather than a single trunk; applied also to a form of lichen which appears shrubby or hair-like. See frutescent.

fucoid adj., n. Of or belonging to the order Fucales, which includes brown algae such as gulfweed and rockweed. A member of the order Fucales. A fossilized cast or impression of such an organism.

fucoxanthin n. Yellowish-brown pigment found in some members of the Chromista, including kelps and diatoms.

fugacious (L. fugax, fugacis: apt to flee) adj. Falling or withering away very early; ephemeral. Cf. caducous, deciduous.

fulcra See fulcrum.

fulcrum (L. fulcrum: support) n. (pl. fulcra) A plant appendage, such as a bract, tendril, stipule, etc.

fulgent (L. fulgere: to flash, glitter, shine) adj. Exquisitely bright; shining; dazzling.

fulgid (L. fulgidus: shiny, bright) adj. Shining; glittering; dazzling; having brief brilliant points or flashes of light.

fuliginous (L. fuliginosus: covered with soot) adj. Sooty; colored by or as if by soot.

fulvous (L. fulvus: yellowish, tawny) adj. Tawny; dull yellowish-brown or yellowish-gray.

fumigant n. A chemical compound used in its gaseous state as a pesticide or disinfectant.

funaliform (L. funalis: made of ropes, forma: shape) adj. In the form of rope; composed of rough fibres.

fundi See fundus.

fundus n. (pl.fundi) Base or bottom; e.g. the neck of capsule or base of peristome tooth.

fungal adj. See fungous.

fungi A plural of fungus.

fungiform (L. fungus: mushrom; forma: shape) adj. Mushroom-shaped.

fungilliform (L. fungulus: little mushroom) adj. Mushroom-shaped.

fungoid (L. fungus: mushroom; eidô: to look like) adj. Mushroom-shaped.

fungous adj. Of, pertaining to, or caused by fungi. Syn. fungal.

fungus (L. fungus: mushroom) n. (pl. fungi, funguses) Any of numerous thallophytes of the Kingdom Fungi (division fungi), comprising the mushrooms, molds, mildew, rusts, smuts, etc.

funicle (L. funiculus: string, small rope) n. The stalk that attaches an ovule to the placenta in the ovary of a flowering plant. It contains a strand of conducting tissue leading from the placenta into the chalaza.

funiculate (L. funiculus: string, small rope) adj. Having a funicle.

funiculi See funiculus.

funiculus (L. funiculus: string, small rope) n. (pl. funiculi). See funicle.

funiform adj. Rope-like.

funnelform adj. Gradually widening upwards, as in the flowers of morning glory.

furan n. An heterocyclic organic compound typically derived by the thermal decomposition of pentose-containing materials, cellulosic solids especially pine-wood. It is toxic and may be carcinogenic. Also known as furane and furfuran. limonoids, etc.

furane See furan.

furfuran See furan.

furanocoumarin See furanocoumarins.

furocoumarin See furanocoumarins.

furanocoumarins n. pl. A group of complex coumarins in which the coumarin structure is prenylated (i.e., a five-carbon unit derived from mevalonic acid is attached); this five-carbon mevalonate-derived unit is usually reduced to two carbons which are part of a furan ring that is attached to a benzene ring; immediate precursors for furanocoumarin synthesis are umbelliferone and isoprene; linear furanocoumarins have the furan ring in line with the benz-2-pyrone nucleus, angular furanocoumarins have the furan ring oriented at an angle to the nucleus. These chemical compounds are produced by a variety of plants. Many are toxic and are produced by plants as a defense mechanism against various types of predators ranging from insects to mammals. This class of phytochemical is responsible for the phytophotodermatitis seen in exposure to the juices of the wild parsnip. In humans, certains furanocoumarins affect the metabolism of certain pharmaceutical drugs. Alos named furocoumarins.

furcate (L. furca: fork) adj. Forked, branching. Cf. bifurcate.

furfuraceous (L. furfur: bran, scale) adj. Made of or covered with scaly particles, such as dandruff; relating to or resembling bran; scaly.

furrowed adj. grooved; e.g. the indentation down the dorsal surface of an exostome tooth of an Acroporium peristome; with channels running lengthwise, including both sulcate grooves and striate thread marks.

fusain n. Fossil charcoal; a component of coal and sedimentary rocks characterized by black color, silky luster and fibrous texture

fusaria See fusarium.

fusarium n. (pl. fusaria) A soil-borne fungus, that cause wilting of vine crops. In many cases the fungus-causing wilt in a particular crop is specific to that crop. These fungi are generally capable of surviving for long periods in the soil.

fuscous (L. fuscus: black, dark) adj. Dark grayish-brown; dusky.

fusiform (L. fusus: spindle; forma: shape) adj. Shaped like a spindle; broadest near the middle and tapering at both ends; narrow (more than 3 times as long as wide) and tapered at both ends.

fusiform initials Found in the vascular cambium, vertically elongated cells the differentiation of which produces vertically-elongated members of the vascular tissue, sieve tubes, vessels, etc.

fusilinid n. One of the so-called 'larger foraminifera' (Foraminiferida) which usually have a fusiform or discoid shape. Many genera are differentiated by rapid development and evolution, making them important index fossils, particularly in Carboniferous and Permian rocks.

fusoid adj. Spindle shaped and tapering to a point at the ends.

Fynbos See Fynbos.

fynbos n. A South African term for the sclerophyll vegetation on plateaus and mountains, similar to the macchia of the Mediterranean region and the chaparral of California.