wallum n. Describe coastal vegetation types growing on sand dunes or flat, undulating country with acid soils and a high water table. Wallum is an aboriginal word for the Wallum Banksia found growing on the coastal lowlands between northern New South Wales and southern Queensland in Australia.

wanting adj. Absent, lacking, nonexistent.

wart n. A firm protuberance.

warty adv. See wart.

water-table n. The level below which the ground is saturated. Any hole in the ground will fill with water when the water-table has been reached. This level often fluctuates with rainfall. The water-table is thus the upper surface of the groundwater. Also : water table.

water table See water-table.

watershed n. A ridge of high land dividing two areas that are drained by different river systems. Also called water parting. The region draining into a river, river system, or other body of water.

wax n. A smooth substance of low melting point (40-80C) obtained from plants (e.g. carnauba wax) or animals (e.g. beeswax, lanolin) or made synthetically. They consist of esters of higher fatty acids than are found in fats, usually with monohydric alcohols. Mineral waxes also exist, the most common being paraffin wax, which is a mixture of the higher hydrocarbons obtained from the distillation of petroleum. Waxes are used in making polishes, candles, mouldings, etc., and in modelling.

webbed adj. With an interlacing network of filaments, fibers, hairs, or veins.

weed n. An aggressive plant which colonizes disturbed habitats and cultivated lands.

weft A loosely interwoven, often ascending growth form; e.g. Thuidium.

welwitschia n. An unusual gymnosperm plant, Welwitschia mirabilis, confined to the deserts of SW Africa. The very short stem bears two strap-shaped waxy leaves, which grow continuously and are up to 1 m long. The long taproot absorbs water from the desert subsoil, and small conelike flowers produce winged seeds. Individual plants may live for more than a hundred years. Phylum: Gnetophyta.

Welwitschia See welwitschia.

whooping cough A highly contagious disease of the respiratory system, usually affecting children, that is caused by the bacterium Bordetella pertussis and is characterized in its advanced stage by spasms of coughing interspersed with deep, noisy inspirations. Also called pertussis.

whorl n. Circle of flowers, parts of a flower, or leaves arising from one point; verticil. An arrangement of appendages, such as branches or leaves, such that all are equally spaced around the stem at the same point, much like the spokes of a wheel or the ribs of an umbrella.

whorled adj. With parts arranged in whorls, as in a leaf arrangement with three or more leaves arising from a node. Syn. verticillate.

wing n. 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.

winged adj. With projecting thin flat membranes or corky outgrowths.

winter annual A plant with seeds germinating in late summer or fall and completing flowering and fruiting in spring or summer of the following year and then dying.

winter bud A hibernating vegetative shoot.

wintergreen n. Any of a genus (Gaultheria) of evergreen plants of the heath family; especially: a low creeping evergreen shrub (G. procumbens) of North America with white flowers and spicy red berries; an essential oil from this plant; flavor of this oil, wintergreen lozenges.

Wolfcampian n. The basal series in the Permian of N. America, underlain by the Virgilian Series (Pennsylvanian), overlain by the Leonardian, and roughly contemporaneous with the Asselian and lower Sakmarian Stages.

wood n. A secondary tissue found in seed plants which consists largely of xylem tissue.

wood ray A radially oriented tier of parenchyma cells that conducts food, water, waste products and other materials laterally in stems and roots of woody plants; rays are ususally continuous across the vascular cambium between the secondary phloem and xylem.

woolly adj. With long, soft, entangled hairs; lanate.

Wordian n. A stage of the Zechstein Epoch, preceded by the Ufimian and followed by the Capitanian.