Glossary of Plant Terms

 

U to Z

U

umbel: an indeterminate inflorescence in which all the flowers or flower stalks (pedicels) arise from one point at the top of the peduncle.

umbellate: with umbels.

umbelliform: in the form of an umbel.

umbel-like: resembling an umbel, or with the inflorescence in umbels.

umbonate: with a knob or projection near the centre of the organ.

unarmed: without spines, thorns or prickles.

undershrub: a small shrub, often partially herbaceous.

understorey: the lower level of woody vegetation in a forest, e.g. small tree layer, Shrub layer or herbaceous ground layer.

undulate: of a margin, wavy, i.e. not flat. cf. sinuate.

unifoliolate: 1-foliolate; a compound leaf reduced to a single leaflet, usually recognized by the articulation or joint near the apex of the petiole. Often mistaken for a simple leaf. In the key 1-foliolate leaves are included with phyllodes in ‘simple’ leaves.

unigeneric: of a family, having only one genus. cf. monotypic.

unisexual: with only one type of functional sexual organ, either ovaries or stamens but not both.

united: fused together.

urceolate: urn-shaped, similar to cup-shaped, but the sides usually higher and narrower at the apex.

V

valvate: opening by valves, e.g. of a capsule.

valve: a lid or segment of an organ which opens or separates at dehiscence, as in a capsule or an anther.

variegated: irregularly coloured with two or more colours on the one surface, as in leaves. cf. concolorousdiscolorous.

variety: a taxonomic category below that of species (and subspecies if both used); differentiates variable populations.

vascular plants: plants containing vascular tissue (ferns, fern allies, cycads, conifers and flowering plants). cf non-vascular plants.

vascular tissue: tissue specialized for the conduction of fluids.

vector: a carrier or transferring agent, e.g. pollen transferred to the stigma by the wind or insect.

vein: a strand of vascular tissue; the primary vein or midvein gives rise to secondary or lateral veins and in turn tertiary veins. See venation patterns.

velvety: very densely covered with fine short soft erect hairs.

venation pattern: the pattern made by the major veins on a surface, such as a leaf.

ventral: of a lateral organ, facing towards the subtending axis. cf. dorsal.

verrucose: warty, covered with warts or wart-like bumps, as in Zieria verrucosa.

verticillate: in a whorl.

vesicle: a bladder-like sac or cavity, adj. vesicular, e.g. of hairs that are bladder-like. Vesicular hairs often collapse and form a silvery layer on the surface of the organ on which they are formed.

vestigial: the remains or trace of an organ which has largely disappeared during evolutionary processes. cf. obsolete, rudimentary.

villous: covered with long weak shaggy hairs, not matted.

vine thickets: Vts; closed stunted communities with a canopy less than 10 m high, overtopped by taller emergents.

viscid: sticky.

W

warm-temperate rainforest: WTRf, closed communities that replace Subtropical Rainforest on poorer soils and under cooler temperature conditions, e.g. at higher elevations and/or increasing latitudes.

warty: tuberculate; covered with warts or wart-like bumps, as in Zieria granulata.

wet sclerophyll forest: an open forest in which mesomorphic (soft-leaved) shrubs form a layer below the trees (usually species of eucalypts). cf. dry sclerophyll forest.

whip branch: long, mostly leafless, terminal branchlets, that aid the plant in finding a climbing support.

whorl: a ring of similar organs arranged in a circle around a central axis, at the same level, e.g. of leaves on a stem and then leaves said to be whorled, or of bracts or floral parts.

whorled: arranged in a circle around a central axis, e.g. of leaves on a stem. cf. pseudo-whorledalternateoppositesub-opposite.

wing: (1) a thin flange of tissue on a stem, petiole or rachis; (2) a membranous expansion of a fruit or a seed, as in Derris involuta (winged pod) or Hakea ochroptera (winged seed).

wings: the pair of lateral petals of a pea flower, in family Fabaceae subfamily Faboideae, as in Derris involuta.

witch’s broom: a disease or deformity in some plants, where the natural structure is changed or a dense mass of shoots grow from a single stem. The resulting structure resembling a broom, as sometimes in Syzygium hodgkinsoniae, Ficus coronata and some mistletoes.

woodland: a plant community dominated by short-boled trees (usually species of eucalypts) that are separated from each other by an average distance equal to 3 to several times the average crown width. There is usually a well-developed understorey of either grasses and other herbs, sedges or hard-leaved shrubs. cf. forest.

woolly: densely covered with matted long hairs. cf. tomentosevillous.

wrinkled: covered with coarse lines or furrows.

X

x: placed after a genus name and before a species name, or between two species names to indicate the taxon is of hybrid origin, as in Citrus x limon.

Z

zygomorphic: of a flower with parts in each whorl, such as sepals and petals and often the stamens, differing in shape, size, position and/or number so that the flower can only be bisected by only one vertical plane to produce similar halves; irregular flowers, bilaterally symmetrical. cf. actinomorphic.

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