valvate: of perianth parts, meeting edge to edge in the bud, not overlapping. cf. imbricate.
valve: a portion of an organ that has fragmented; of a capsule, the teeth-like portions into which the dehiscing part of the pericarp splits at maturity.
vascular: specialised for conduction of fluids; vascular plants: plants containing specialised conducting tissues.
vein: a strand of vascular tissue.
velamen: a water-retaining outer layer of the aerial roots of some epiphytes, especially orchids.
velum: a membranous covering; a veil.
venation: the arrangement of veins in a leaf.
ventral: of a lateral organ, facing towards the subtending axis; of a thallus, facing towards the substratum. cf. dorsal.
vernation: the arrangement of unexpanded leaves in a bud. cf. aestivation.
verrucose: covered with wart-like outgrowths, warted.
verruculose: covered with closely spaced, minute wart-like outgrowths.
versatile: of anthers, swinging freely about the point of attachment to the filament, which is approximately central. cf. basifixed, medifixed.
verticil: a whorl or circular arrangement of similar parts around an axis.
verticillaster: a false whorl of opposed cymes.
verticillate: arranged in one or more whorls; a false whorl of flowers in a pair of opposite dense cymes, especially in Lamiaceae.
vesicle: a bladder-like sac or cavity filled with gas or liquid.
vessel: a capillary tube formed from a series of open-ended cells in the water-conducting tissue of a plant.
vestigial: reduced from the ancestral condition and no longer functional. cf. obsolete, rudimentary.
vexillum: = standard.
villous: shaggy with long, weak hairs. cf. hirsute.
viscid: of a surface, sticky; coated with a thick, syrupy secretion.
viscidium: in Orchidaceae, a viscid part of the rostellum which is clearly defined and removed with the pollinia as a unit, serving to attach the pollinia to an insect or other pollination vector.
viscous: of a liquid, not pouring freely; having the consistency of syrup or honey.
viviparous: of seeds or fruits, germinating before being shed from the parent plant.
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wallum: coastal vegetation on sandy acidic soils, in south-eastern Queensland.
whorl: a ring of leaves, bracts or floral parts borne at the same level on an axis. cf. cyclic, spiral.
wing: a membranous expansion of a fruit or seed, which aids dispersal; a thin flange of tissue extended beyond the normal outline of a stem or petiole; a lateral petal of a flower in Fabaceae.
xeromorph: a plant having structural features usually associated with plants of arid habitats (such as hard or succulent leaves) but not necessarily drought-tolerant. cf. scleromorph, xerophyte.
xerophyte: a drought-tolerant plant. cf. xeromorph.
xylem: the tissue, in a vascular plant, that conducts water and mineral salts from the roots to the leaves.
zygomorphic (= irregular): of a flower or calyx or corolla, bilaterally symmetrical, symmetrical about one plane only, usually the plane that bisects the flower vertically along the longitudinal axis. cf. actinomorphic, peloric.
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Last updated on 13 May 1999.