Distribution: Silver wattle occurs mainly in the Australian Alps from northern New South Wales to mid-western Victoria, and in Tasmania. The latitudinal range is 29-43o S. It is found at altitudes mainly between 250-900 m but can grow up to 1500 m. It has become naturalised in South Australia and south-eastern Queensland. (ACT, NSW, VIC, TAS)
A fast growing, nitrogen-fixing shrub or tree 6-30 m tall. The branchlets are somewhat hairy and with a waxy grey bloom that can be rubbed off. The foliage is bipinnate with a midrib 4-10 cm long and 10-26 pairs of pinnae on which are 20-50 pairs of fine pinnules (small leaflets) 2-5 mm long and about 0.5 mm wide. The golden yellow flowers are in globular heads. The pod is more or less straight, flat, raised over the seeds and light purplish brown. There are about 53 000 seeds per kilogram. Seeds need pre-treatment with boiling water for one minute to promote germination.
Ecology/Way of Life:
The distribution is in cool to warm sub-humid areas where the average annual number of frosts is 20-80. Annual rainfall is 600-1000 mm with a summer maximum in the north of its range and a winter maximum in the south. It experiences 20-80 frosts a year and is one of the most frost tolerant acacias. It grows mainly in hilly country on steep slopes and along stream banks, usually on moderate to well-drained soils. Silver wattle grows best on sheltered sites in open forest or tall open forest amongst big eucalypts, such as Eucalyptus regnans and Eucalyptus delegatensis.
Interaction with Humans/Threats:
It is widely cultivated as an ornamental or farm tree where it is useful in wind breaks and for erosion control. It is the 'mimosa' of southern Europe where it has been used for cut flowers since early times. In southern France it is a source of aromatic oils for perfumery. Tannin, extracted from the bark, is sometimes used to prepare leather but the quality is poor compared to that produced by the black wattle (Acacia mearnsii). Wool may be dyed with its leaves to yellow-fawn or green. The heartwood varies from light brown to pinkish and has been used for furniture. It is also a very good quality pulpwood and a satisfactory fuelwood. Silver wattle is a serious pest in South Africa and parts of India where it has escaped cultivation by means of its prolific seed production and ability to produce root suckers.
Other Comments:Acacia dealbata was named in 1822 by Heinrich F. Link - Professor of Botany, Berlin University, and Director, Royal Botanic Gardens, Berlin; the name is based on Greek: akakia = a thorny plant, specifically Acacia arabica; and Latin: dealbatus = covered with white powder, referring to the whitish or silvery appearance of the canopy.
Boland, D.J., Brooker, M.I.H., Chippendale, G.M., Hall, N., Hyland, B.P.M., Kleinig, D.A., Johnston, R.D. and Turner, J.D. 1984. Forest trees of Australia. 4th ed. Nelson and CSIRO, Melbourne. 687p.
Doran, J.C. and Turnbull, J.W. (eds.) 1997. Australian trees and shrubs; species for land rehabilitation and farm planting in the tropics. ACIAR Monograph no. 24. Australian Centre for International Agricultural Research, Canberra. 384p.
Topics:Aromatic oils Plant structure Firewood Invasive species/Weeds Vegetation types Windbreak Aboriginal Resources Germination Climatic zones Soils Nitrogen-fixation
Text & map from Australian Trees and Shrubs, courtesy Australian Centre for International Agricultural Research; text edited by J. Turnbull; photographer Kelly, D. © ANBG.
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