Citation: H. F. Link, Enum. Plant. Hort. Berol. 2:445 (1822).

Derivation: dealbatus (Latin)--whitened, covered with a white powder-like substance.

Synonymy: Racosperma dealbatum (Link.)Pedley, Austrobaileya 2:258 (1987).

Common name: Silver wattle

Description:
Medium sized trees to 12 m high, in eastern States it may obtain a height up to 30 m, canopy rounded and glaucous; branches angular, striate, pruinose and hoary with a minute pubescence; bark smooth, grey-brown to dark grey on the trunk, suckers freely if the roots are damaged.

Leaves bipinnate; petiole 0.5-2 cm long; rachis 2-10 cm long, angular, pubescent, with a raised gland on the upper surface at the junction of each pair of pinnae; pinnae 10-26 pairs; pinnules 20-50 pairs crowded, linear-oblong, more or less densely pubescent, 2-5 mm long, 0.4-0.7 mm broad,

Inflorescences racemose or panicled; flower-heads lemon to bright yellow, sweet-scented, 25-35-flowered; peduncles pubescent, c. 6 mm long; flowers 5-merous.

Legumes oblong, 5-8 cm long, 8-12 mm broad, straight or slightly curved, flat but raised over seeds, glaucous or light purplish-brown, margins slightly constricted. Seeds longitudinal in legume, ellipsoid; funicle short, expanded into a small aril.

Distribution:  Introduced from the eastern States. Minor occurrence in the Southern Lofty region, mainly in the higher rainfall areas of the Adelaide Hills, also found occasionally in the South-Eastern region around Penola. Soils; shallow red clay and grey-brown calcareous loamy earths. Rainfall 700-1 200 mm. Also N.S.W., A.C.T., Vic. and Tas. Flowering time: July — September.

SA Distribution Map based on current data relating to specimens held in the State Herbarium of South Australia

Biology: No text

Related taxa: Sometimes confused with Acacia mearnsii which differs mainly in having prominent raised glands, between the pinnae pairs. A. decurrens differs in its glabrous dark green spaced pinnules.

Taxonomic notes: A. dealbata is listed as being cultivated in Adelaide in 1859, 1871, 1878 and a cultivated herbarium specimen of 1895 survives. The first material described as adventive was collected by Professor J. B. Cleland from near Crafers in 1944.

Two collections of Amyema pendulum, drooping mistletoe have been made on Acacia dealbata. This mistletoe is more commonly found on species of Eucalyptus.

The fixation of nitrogen by A. dealbata seedlings was studied by Hopmans et al. (1983). Activity was markedly affected by soil moisture and was significantly reduced at wilting point. It was also reduced after long dark periods but only when this exceeded 12-15 hours. The addition of nitrogen fertiliser caused a rapid decline of nitrogen fixation. Increasing soil salinity also reduced activity though A. dealbata is not normally a species found in sub-saline areas.

A. dealbata was included in Forest Trees of Australia, Boland et al. (1984) where a description, illustrations and a map are given.

A. dealbata is now naturalised in New Zealand, Webb et al. (1988), and has become well-established in South Africa, Ross (1975) as well as southern Europe.

Henderson (1989) has shown that A. dealbata is one of the most prominent woody invasive aliens in the grassland biome of Orange Free State.

A. dealbata is the 'Mimosa' of southern Europe where it was early introduced and is grown for florists use. The timber is of poorer quality than many other Acacia but has been used for glued products, clothes pegs, pulping and woodwool.

In southern France A. dealbata is one of several species of Acacia to provide not only cut flowers but also a source of aromatic oils for perfumery, Poucher (1984).

Payne (1989) described the cultivar A. dealbata cultivar Kambah Carpet a prostrate form growing to 20 cm high and 3 m across. It was first recognised in Canberra in 1982 and has to be propagated by cuttings or suckers.

Wool may be dyed with A. dealbata leaves to yellow-fawn or green depending on the mordant used, Martin (1974).

Cultivation: Widely cultivated as an ornamental tree within Australia and also overseas. It prefers cool moist gullies, where they can be seen at their best, but grows also in drier areas such as the Adelaide Plains. Produces a gum arabic substitute and sometimes used for tanning but of inferior quality. Fast growth rate.

Author: Not yet available

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