actinomorphic:  Radially symmetrical; divisible into equal halves by two or more planes drawn through the middle.

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

acute:  Tapering to a sharp, pointed apex with more or less straight sides; broader than acuminate.

adpressed:  Of parts that are lying close together, but are not fused.

alternate:  (of leaves) Arranged with one leaf per node along the stem. (compare opposite)

anther:  The pollen-producing, apical part of the stamen (sometimes sessile; without a filament).

apex (pl. apices; adj. apical):  The point farthest from the point of attachment.

appressed:  Pressed close or flat.

auct.:  Denotes a name applied by authors to the wrong entity.

auriculate:  With ear-shaped lobes (as the base of leaves).

awl-shaped:  Narrowly triangular and small.

awn:  A narrow, bristle-like organ.

axil (adj. axillary):  The upper angle between an axis and a lateral organ (as between a stem and a leaf).

axis:  A straight line through the center of a structure around which the parts are usually symmetrically arranged (geom.); the main stem (bot.).



basal:  At or pertaining to the point of attachment.

basifixed:  Of an anther: attached to the filament at its base.

bearded:  Bearing tufts of long hairs.

bifid:  Two-cleft or two-lobed.

bilabiate:  Two-lipped.

bisexual flower:  A flower with both stamens and pistils.

bract:  A modified leaf near a flower or inflorescence, often reduced.

bracteole:  A secondary bract often borne on a petiole.

bristle:  A stiff hair or hair-like structure.


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

campanulate:  (of a corolla, perianth or calyx tube) Bell-shaped; with a broad base, sides curving to a flared rim.

capitulum:  see head.

carpellate:  Of flowers bearing carpels (female reproductive parts) and lacking stamens.

caudate:  Tapering to a long, tail-like appendage.

chaffy:  With thin, dry, membranous scales or bracts.

ciliate:  With a marginal fringe of hairs.

claw:  The narrowed base of some petals. (compare limb)

compound:  With two or more like parts, as in a compound inflorescence or compound leaf.

compound leaf:  A leaf divided into two or more leaflets.

connate:  Union of like parts (fusion).

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

corona:  An appendage between the corolla and the stamens.

corymb:  A flat-topped or round-topped racemose inflorescence.

corymbose:  (of an inflorescence) Corymb-like or having flowers borne in corymbs.

cultivar:  A horticultural race or variety of a plant that has originated and persisted only under cultivation.

cyathium:  A specialized inflorescence type occurring in the Euphorbiaceae consisting of unisexual flowers enclosed in a cup-shaped involucre.

cyme:  A determinate, usually flat-topped or convex inflorescence in which the terminal flower blooms earliest.



declinate:  Curved downward.

decurrent:  (of a leaf) Extending downward along the stem from the point of insertion.

decussate:  (of opposite leaves) Arranged on the stem in pairs, with alternating pairs at right angles.

deflexed:  Bent abruptly downward.

determinate:  (of an inflorescence) With the terminal or central flower opening first, so that the main axis does not elongate further.

disbudded:  (of an inflorescence) Having all subtending axillary buds removed, leaving only a terminal bud, so that only one large flower (or head) develops.

disc floret:  A flower with an actinomorphic, sympetalous corolla on heads in the Asteraceae.

discoid:  With disc flowers, as in Asteraceae heads.

dissected:  (of leaves) Cut or lobed in any way, but not compound.

distichous:  (of leaves or flowers) Distinctly arranged in two ranks along an axis; leaves may be opposite or alternate.

dorsifixed:  (of an anther) Attached to the filament at its back.

double:  (of a flower or head) With more than the normal number, or extra whorls, of petals, tepals, perianth segments, or petaloid sepals; in the Asteraceae, heads with more than the normal number of ray florets.



equal:  Of plant parts being compared, where the parts are similar in length or terminate at the same point.

elliptic:  Oval.

emarginate:  With a shallow notch at apex.

ensiform:  Sword-shaped (usually to describe larger parts than awl-shaped.

entire:  Having a continuous margin that is not toothed or lobed.

epigynous:  With stamens, petals and sepals (or perianth whorls) attached at the top of the ovary.

exserted:  Projecting or extending beyond surrounding parts (as, e.g. stamens projecting from a perianth tube).


filament:  The stalk of the stamen bearing the anther.

filiform:  Thread-like; long and thin.

floret:  One of the small individual flowers within a dense cluster of flowers.

flower:  The reproductive structure of the angiosperms. A complete flower consists of stamens, pistils, and a perianth of calyx and corolla (or tepals or perianth parts).

funnelform:  (of a corolla, perianth or calyx tube) Funnel-shaped; flaring with straight sides from a narrow base.


glabrous:  Without hairs.

globose:  Spherical.

gynostegium:  The specialized structure formed from the adnation of the stamens and the stigmas in the Asclepiadaceae.



head:  A dense, clustered inflorescence of sessile or subsessile flowers on a very short axis.

hort.:  1) The misapplication of a name by gardeners that is actually a validly published name for a different entity; or 2) to denote a name of horticultural origin published in writings of confused authorship or of no standing as a valid publication.

hybrid:  A plant produced from a cross between genetically distinct parents or different species or genera.

hypanthium:  The cup-shaped structure formed from the fusion of the basal parts of the calyx, corolla, and stamens, on the rim of which these parts arise.


imbricate:  Overlapping in a regular pattern, like shingles on a roof.

imperfect:  Of a flower, lacking either stamens or pistil(s); unisexual.

indeterminate:  (of an inflorescence) With lower or outer flowers opening first, so that the main axis continues elongating.

inferior ovary:  An ovary that lies beneath the point of attachment of the other floral whorls; can also be interpreted as an ovary that is fused to a hypanthium. (compare superior ovary)

inflexed:  Curved or bent inwards toward the axis.

inflorescence:  The arrangement of flowers on the floral axis.

involucel:  A secondary involucre, as in the Apiaceae.

involucre:  A whorl or whorls of bracts subtending a flower or inflorescence.

irregular:  Not divisible into equal halves.


keel:  A prominent longitudinal ridge.

keeled:  Folded longitudinally, with or without a longitudinal midrib.



labellum:  A lip.

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

lateral:  Of, at, or from the side.

leaflet:  One of the leaf-like units of a compound leaf.

lenticular:  Lentil-shaped; biconvex.

ligulate head:  In the Asteraceae, a head bearing only ray florets.

ligule:  The strap-shaped corolla limb of the ray florets in the Asteraceae.

limb:  Expanded part of a petal, tepal or leaf or of a corolla or perianth tube. (compare claw)

lobe:  (of a corolla, perianth, or calyx tube) One segment of the limb of the tube; the expanded, unfused part of a petal, tepal, sepal, or perianth segment.

locule:  A cavity or compartment in an organ, as the pollen-producing compartment of an anther.


merous:  Suffix indicating the number of parts in a flower, e.g., 5-merous = 5 corolla lobes, 5 carpels, etc.

midrib:  The main or central vein, line or rib in a leaf or perianth segment.

monoecious:  Having separate male and female flowers on the same individual plant.

ms:  Manuscript; not a published name.

mucronulate:  Diminutive of mucronate (terminating with a short, sharp, abrupt tip).



node:  The place on a stem where a leaf or leaves originate; or on an axis or other structure where organs arise.

non:  Latin for 'not'. Used to differentiate between various applications of a name to different plant entities by different authors.


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

oblong:  Two to four times longer than wide, with parallel sides.

opposite:  (of leaves or other structures) Two borne at the same point on opposite sides of an axis. (compare alternate)

orbicular:  Round in outline.

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

ovoid:  Egg-shaped in three dimensions. (compare ovate)


palmate:  (of leaves or venation) With lobes, leaflets, divisions or veins originating from the same point. (compare pinnate)

panicle:  An indeterminate, branched (often much-branched) inflorescence; the ultimate units may be of a different inflorescence type.

paniculate:  In the form of a panicle; bearing panicles.

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

pedicel:  The stalk of a single flower in an inflorescence.

pedicellate:  Borne on a pedicel.

peduncle:  The stalk of a flower cluster or inflorescence.

pendent:  Hanging downwards.

perfect:  (of a flower) With both functional male and female reproductive organs (stamens and pistils); bisexual.

perfoliate:  (of a leaf) With the margin completely surrounding the stem, so that the stem appears to pass through the leaf.

perianth:  Collective term for the calyx and corolla of a flower; also used specifically for whorl(s) that cannot be differentiated into calyx and corolla.

perianth part; perianth segment:  One unit of the perianth.

petal:  One segment of the corolla, used when the petal segments are completely separate.

petiole:  The stalk of a leaf.

petiolule:  The stalk of a leaflet in a compound leaf.

phyllary:  An involucral bract in the Asteraceae.


phyllotaxy:  The arrangement of leaves on the stem.

picotee:  Term to describe a narrow band of color at the distal edge of a petal, tepal, or perianth segment.

pinnate:  (of leaves or venation) With more than three leaflets, lobes or veins arranged in two rows along an axis. (compare palmate)

pinnatifid:  (of leaves) Deeply pinnately lobed half way or more, but not reaching, the midrib.

pinnatisect:  Pinnately cut or lobed to the midrib.

pistil:  The female reproductive organ, usually consisting of an ovary, a style, and a stigma, formed from one or more carpels.

pollen presenter:  A term for the style-end in some flowers, in which pollen is deposited on the style-end by anthers in the same flower; the pollen is collected by pollinators from the style-end rather than the anthers directly.

pollinium:  A mass of waxy, coherent pollen grains transported as a unit in the Asclepiadaceae or Orchidaceae.

poricidal:  (of anthers) Having pores through which pollen escapes.


quilled:  (of petals or ray floret limbs) Nearly terete, hollow, or involute; quill-like; (of cultivars) with quilled or petals or limbs.



raceme:  An indeterminate, unbranched inflorescence having pedicelled flowers on a usually elongated axis.

racemose:  Raceme-like or bearing racemes.

radiate head:  In the Asteraceae, a head consisting of both ray florets and disc florets.

ray:  One of the branches of an umbel.

ray floret:  A zygomorphic flower with a strap shaped corolla on heads in the Asteraceae.

receptacle:  The enlarged or elongated apex of the pedicel on which the flower parts are borne; in the Asteraceae the enlarged apex of the peduncle on which the florets in a head are borne.

recurved:  Curved downward or backward.

reflexed:  Abruptly curved or bent downward.

regular:  see actinomorphic.

revolute:  With margins rolled downward, or to the lower side.

rotate:  Wheel-shaped, of a corolla or perianth with a short tube and spreading, horizontal limb.



s.l.:  see sensu lato.

salverform:  (of a corolla or perianth) With a long, slender tube and an abruptly expanded, flat limb.

scale:  Short, thin, flat bracts or hairs.

scape:  A leafless peduncle arising from the ground, and bearing flower(s) or an inflorescence.

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

semi-double:  Partly or not fully double.

sensu lato:  Latin for "in the broad sense".

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

sessile:  Attached without a stalk.

simple leaf:  Not compound; not divided into leaflets.

single:  (of a flower or head) Not bred to be double; having the normal number or whorls of petals, perianth parts, tepals, or, in the Asteraceae, ray florets.

sinus:  The indentation or space between two units, as the lobes on a leaf or petal.

spadix:  A spike with a fleshy axis, and small, densely crowded flowers.

spathe:  A large, sometimes colored bract enclosing or subtending an inflorescence.


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

spike:  An indeterminate, unbranching inflorescence of sessile flowers or flower clusters on a usually elongated axis.

spikelet:  A small spike.

spray:  (of an inflorescence) With the apical bud removed, so that all axillary flowers (or heads) develop; a full inflorescence with numerous flowers open at the same time.

spur:  A sac-like projection or extension of a petal or sepal.

stamen:  The male reproductive organ, consisting of a pollen-bearing anther, and a filament.

staminate:  Bearing stamens but not pistils.

staminode:  A sterile stamen, often modified in appearance and with an empty, often much reduced anther that does not produce pollen.

sterile:  Infertile, as a stamen without an anther or a flower without a pistil.

stigma:  The apical, pollen-receptive part of the pistil.

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

stylopodium:  A disc-like enlargement of the style bases present in some Apiaceae.

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

subtend:  Situated directly beneath an organ, as bracts beneath an inflorescence.

superior ovary:  Situated above the point of attachment of the other floral whorls. (compare inferior ovary)

sympetalous:  With the petals united, sometimes only at the base.

synsepalous:  With the sepals united, sometimes only at the base.


tepal:  A member of the perianth, when it is in two whorls that are alike in size, color and texture, and cannot be differentiated into a calyx and corolla. Used primarily for monocot flowers.

ternate:  In threes.

throat:  The orifice of a corolla, calyx or perianth tube, or the region between the tube and the limb.

toothed:  Bearing a margin of small projections alternating with indentations (general term).

trigonous:  Three-angled.

tubular:  (of a corolla, perianth or calyx tube) Tube-shaped, cylindrical; narrow and elongate with more or less straight sides.

turbinate:  Top-shaped.



umbel:  A flat to convex inflorescence in which the flower pedicels (called rays) all arise from the same point.

unisexual flower:  A flower with either stamens or pistils but not both.

urceolate:  (of a corolla, perianth or calyx tube) Urn-shaped; more or less ovoid or globose, and constricted near the rim.


var.:  Variety; a taxonomic category below the subspecies level.

ventral:  Of the inner or axis side of an organ.


whorl:  Three or more similar organs arranged in a circle at the same point around an axis.


zygomorphic:  Bilaterally symmetrical; divisible into two equal halves along only one plane.