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abaxial: on the side that is away from the axis (in leaves, the underside)

achene: a dry, indehiscent, one-seeded fruit, with seed attached to pericarp at a single point

acuminate: tapering gradually to a point and forming more or less concave sides

adaxial: on the side that is towards the axis (in leaves, the upper side)

alveolate: honeycombed

anatropous ovule: an ovule which is inverted and adnate to the funiculus, with the micropyle adjoining the funiculus

annular: forming a ring

antrorse: (adv. antrorsely) curved or bent toward the apex (as in 'antrorsely barbed')

apex: the point farthest from the point of attachment

areole: in the Cactaceae, a small, specialized area on the stem bearing spines and hairs

article: section of a fruit separated from other sections by a constricted joint

awn: a narrow, bristle-like organ, as on the glumes or lemmas of grasses

axile: on or of the axis

axis: a straight line through the center of a structure around which the parts are usually symmetrically arranged (geometry); the main stem (botany)


barbed: (of awns or bristles) with short, sharp, hairlike processes

basal: at or pertaining to the point of attachment

berry: an indehiscent, few- to many-seeded fruit from a single pistil, in which the pericarp becomes entirely fleshy

bifid: two-lobed or two-cleft

bristle: a stiff hair or hair-like structure

bulb: an underground vertical shoot that has modified leaves (or thickened leaf bases) that are used as food storage organs by a dormant plant


callus: the hard base of grass florets or spikelets, just above the point of disarticulation

calyx: the outer whorl of the perianth; all the sepals of a flower

capsule: a dry, dehiscent fruit formed by two or more carpels

carpopodium: an elongation of the base of the gynoecium which looks distinct, as in the achenes of some Asteraceae

cartilaginous: tough and firm but flexible; like cartilage

caruncle: a localized outgrowth of the seed coat near the hilum of the seed in some members of the Euphorbiaceae; it functions as an eliaosome

caryopsis: a dry, indehiscent, one-seeded fruit in which the seed coat is fused to the pericarp in the hilar region only, as in most grasses

caudate: tapering to a long, tail-like appendage

chalaza: the region at the base of the ovule where the integuments are inserted

chartaceous: papery

ciliate: with a marginal fringe of hairs

clavate: club-shaped, with attachment at or near narrow end (compare obclavate)

commissure: the face along which two carpels join, as in the Apiaceae

compressed: flattened; in grasses, used to denote compression (not necessarily flattened) either laterally or dorsiventrally

connivent: converging but not fused

cordate: heart-shaped, with attachment at or near the broad end (compare obcordate)

coriaceous: leathery

corolla: the inner whorl(s) of the perianth; all the petals of a flower

cotyledon: a primary leaf of the embryo

craspedium: a one-carpellate fruit splitting transversely into one-seeded segments; seed-bearing segments separate from each other and from the persistent sutures (see fruits of Mimosa diplotricha and Mimosa pigra)

crenate: having a margin with low, rounded or scalloped projections

cyanobacteria: unicellular, filamentous or colonial photosynthetic bacteria in the kingdom Eubacteria, formerly known as "blue-green algae"


deciduous: falling off; not persistent

dehiscent: (v. dehisce) splitting open at maturity to release contents (of a fruit)

dimorphic: occurring in two forms

dioecious: having separate male and female flowers on different individuals of the same species

discoid: resembling a disc

disseminule: detachable plant part capable of being disseminated and of propagating, commonly a seed or fruit

dorsal: the back of an organ; the side away from the axis (compare ventral)

dorsiventral: pertaining to the dorsal and ventral surfaces

drupe: a fleshy, indehiscent fruit with a stony endocarp

drupelet: one drupe of a fruit with multiple drupes, as in blackberries


elaiosome: A lipid and protein-rich fleshy structure attached to some seeds and fruits, it attracts ants which then disperse the disseminule. Examples include the caruncle in the Euphorbiaceae, the aril (outgrowth of the funiculus) in the Fabaceae, and the structure found at the base of some fruits in the Asteraceae.

elliptic: oval

emarginate: with a shallow notch at apex

embryotega: an outgrowth on the seed coat, as in the Commelinaceae

emersed: rising from and standing above the water

endocarp: the inner layer of the pericarp

endosperm: nutritive starch- and oil-containing tissue present in many seeds

exocarp: the outer layer of the pericarp


falcate: shaped like a scythe or sickle

fascicle: a highly reduced branch of a spicate grass panicle consisting of 1–3 whorls of free or fused bristles disarticulating with the spikelets at maturity

fertile floret: a grass floret capable of producing fruit; the fertile floret may possess both male and female, or just female, reproductive structures

flanged: with a projecting rim or edge

floret: the unit of a grass spikelet consisting of a flower or caryopsis, with lemma and palea

frond: the leaf of a fern

funiculus: stalk by which the ovule (later seed) is attached to the placenta in the fruit

fusiform: spindle-shaped; broadest at the middle and tapering at both ends


geniculate: bent like a knee

gibbous: swollen on one side

glabrous: without hairs

glistening: sparkling with reflected light

globose: spherical

glochidium: (pl. glochidia) a hair-like process bearing an anchor-like tip, that projects from the surface of microsporangial massulae in the Salviniaceae

glossy: shiny

glume: one of the (usually) two bracts at the base of a grass spikelet

granular: having a grainy surface


hilar: of or relating to a hilum

hilum: on seeds, the scar indicating where the funiculus was attached; on grass caryopses, the scar visible on the outer caryopsis surface revealing where the seed is attached on the inner fruit wall surface

hippocrepiform: horseshoe-shaped

hyaline: thin, membranous, and translucent or transparent

hypocotyl: portion of the embryonic axis below the cotyledons and above the radicle


incumbent: (of cotyledons) having the dorsal side of one cotyledon resting against the radicle

indehiscent: not opening on its own, as in a fruit

indurate: hardened

integument: the outer cell layer (or layers) of the ovule that develops into the seed coat

internode: portion of a stem between two nodes

involucre: in the grasses, a whorl or cluster of bracts or bristles subtending a floret or spikelet

isthmus: (pl. isthmi) a narrow strip of tissue connecting two larger parts


keel: a longitudinal ridge formed by the lengthwise folding of a structure, such as a lemma or palea


lanceolate: lance-shaped; widest point below the middle, tapering to the apex (compare oblanceolate)

lateral: of, at, or from the side; in grasses, can refer to the sides adjacent to the dorsal and ventral sides

legume: a usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures

lemma: in grasses, the lower of the two bracts subtending the flower or caryopsis (compare palea)

lens: a mound, pad, or area of tissue situated near the hilum on seeds in the Mimosoideae and Caesalpinioideae

lenticular: lens-shaped; biconvex

loculicidal: dehiscence or splitting along the walls of the locules (chambers or cavities) of a fruit, rather than along the septa (compare septicidal)

loment: a usually dry fruit derived from a single carpel that breaks transversely into one-seeded fruit segments

lomentoid: resembling a loment

lustrous: semiglossy


marginal: at, on, or close to the margin or border

massula: (pl. massulae) in Azolla, a mucilaginous group of microspores within the microsporangium

megasporangium: A hollow structure in which megaspores (haploid spores that develop into female gametophytes) are produced. In Azolla, the megasporangium (or megasporocarp) is in two parts. The lower part contains only one megaspore, and the upper part is filled with 'floats'.

membranous: thin, more or less translucent, flexible; like a membrane

mericarp: a one-seeded section (carpel) of a schizocarp, as in Apiaceae fruits (compare schizocarp)

mesocarp: the middle layer of the pericarp

micropyle: an opening in the integuments of an ovule usually acting as a passage for the pollen tube

microsporangium: a hollow structure in which microspores (haploid spores that develop into male gametophytes) are produced

moniliform: cylindrical and constricted at regular intervals; like a string of beads

monoecious: having separate male and female flowers on the same individual

mottled: with colored spots, streaks, or blotches of a different color

mucronate: terminating with a short, sharp, abrupt tip

mucronulate: diminutive of mucronate

multiseriate: occurring in more than one series

muricate: rough with small, hard, sharp projections


obclavate: club-shaped, with attachment at or near the broad end (compare clavate)

obconic: cone-shaped, with attachment at or near the narrow end

obcordate: heart-shaped, with attachment at or near the narrow end (compare cordate)

oblanceolate: lance-shaped, with attachment at or near the narrow end (compare lanceolate)

oblique: in a slanting direction or position, neither horizontal nor vertical

obovate: egg-shaped in outline, with attachment at or near the narrow end (compare ovate, ovoid)

obpyramidal: pyramid-shaped, with attachment at or near the narrow end (compare pyramidal)

obtrullate: trowel-shaped, with attachment at or near the narrow end (compare trullate)

obtuse: with a blunt or rounded apex

omega: the last letter in the Greek alphabet

orbicular: circular in outline

ovate: egg-shaped in outline, generally with attachment at or near the broad end (compare obovate, ovoid)

ovoid: egg-shaped in three dimensions


palea: in grasses, the uppermost bract enclosing the flower or caryopsis (compare lemma)

palmate: with leaflets or lobes radiating from the base of the leaf

papillate: bearing minute, rounded, nipple-like projections

pappus: the modified calyx in the Asteraceae, composed of hairs, bristles, awns, or scales

pedicel: the stalk of a flower, inflorescence, or grass spikelet

pedicellate: borne on a pedicel

perianth: collective term for calyx and corolla of a flower

pericarp: the fruit wall

perisperm: seed nutritive tissue comparable to the endosperm, but derived from the nucellus – maternal tissue

pilose: having thin, soft, long hairs

pinnae: a leaflet or primary division of a pinnately compound leaf, as in ferns

pinnate: with leaflets on each side of a common axis in a featherlike arrangement

pinnule: smallest divisions of a leaf which is doubly compound, especially in ferns

placenta: place inside the ovary that bears ovules

plano-convex: flat on one side, convex on the other

pleurogram: a U-shaped line on both seed faces resulting from modification of the face of the ovule during seed development, present in some species' seeds in the Fabaceae subfamilies Mimosoideae and Caesalpinioideae

plumose: (of a hair or bristle) feather-like

puberulent: (or puberulous) bearing minute, soft hairs

pubescent: bearing hairs

punctiform: like a point

pyramidal: pyramid-shaped (compare obpyramidal)


quadrate: more or less square


rachilla: the main axis of the spikelet in grasses

rachis: the main axis of the inflorescence in grasses or of a compound leaf (frond) in ferns

radicle: the embryonic root of the embryo

raphe: a ridge or seam on a seed formed by the portion of the funiculus adnate to the ovule, as in anatropous ovules

reniform: kidney-shaped

reticulate: in the form of a network; netted

revolute: with margins rolled downward, or to the lower side

rhizoid: a rootlike structure lacking xylem and phloem, as in algae and fungi

rhizome: a thickish horizontal underground stem producing roots and shoots

rhombic: diamond-shaped in outline; having the form of a rhombus

rugose: wrinkled


scaberulous: rough to the touch because of minute projections

scale: general term for short, thin, flat bracts or hairs

scarious: dry, thin, membranous, non-green, more or less translucent

schizocarp: a dry fruit that splits into two or more one-seeded indehiscent segments (carpels) (compare mericarp)

scurfy: covered with small, branlike scales

scutellum: the single, relatively large cotyledon of a grass embryo

sectoroid: in the form of an orange or apple section

sepal: a member of the outer envelope of a flower (calyx)

septicidal: dehiscence or splitting along the septa of a fruit, rather than along the walls of the locules (compare loculicidal)

septum: (pl. septa) a dividing cross wall or partition

serrate: having a saw-toothed margin, i.e., a margin notched with toothlike projections

serrulate: a minutely serrate margin

sessile: attached without a stalk

spatulate: like a spatula; rounded at the apex, with base long and tapered

spicule: a small, pointed, epidermal appendage

spikelet: basic unit of the grass inflorescence, commonly consisting of a pair of glumes and one to many florets

sporangium: a structure in which spores are produced, as in ferns

spore: in ferns, a haploid reproductive structure adapted for dispersal and surviving for extended periods in unfavorable environmental conditions

stellate: star-shaped; with radiating branches

sterile: lacking male and/or female flower parts; also, not producing fruit or seed

stipe: a stalk

stipitate: borne on a stalk

stolon: a horizontal stem at the ground surface, forming adventitious roots at the nodes or the apex, and forming new plants

striate: having fine, parallel lines, grooves, or ridges

style: in a flower, the narrow and elongated part of the pistil between the stigma and the ovary

style base: remnant of a style, as at the apex of Asteraceae achenes

sub-: a prefix meaning slightly, somewhat, or nearly (used with a descriptive term), or below (used with an anatomical term)

submersed: under water, submerged

suture: a line of fusion; a seam


tannic: astringent, bitter-tasting

tawny: brownish-yellow; tan

tepal: a member of the perianth, when it cannot be differentiated into a calyx and corolla

terete: approximately circular in cross section; width and thickness approximately equal

testa: seed coat

tomentellous: slightly tomentose

tomentose: pubescence that is bent and matted, forming a woolly coating; often the hairs are silver or gray-colored

transverse: lying, situated, or placed across

trichome: a hair or hairlike outgrowth of the epidermis

trullate: trowel-shaped, generally with the attachment at or near the broad end (compare obtrullate)

truncate: terminating abruptly, as if cut straight across

tuberculate: bearing small, warty, swelling, rounded, or variously shaped projections

turion: a perennating bud produced by many aquatic plants, which detaches from the parent plant and remains dormant until the following spring


umbo: a rounded protuberance on both faces of some seeds in the Mimosoideae, such as those of Prosopis

undulate: wavy-margined

utricle: a dry, thin-walled fruit with a free single seed


valve: in fruits, one of the parts into which a fruit separates at maturity

ventral: of the side of an organ facing the axis (compare dorsal)

verrucose: covered with wartlike projections

villous: covered with long, soft, fine hairs

vitta: (pl. vittae) an oil or resin tube in the pericarp of many Apiaceae fruits


waisted: in grass caryopses, refers to an embryo visible on the caryopsis surface that is constricted in the middle