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.

vernicose: varnished.

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.

Australian Biological Resources Study