Common Name: Silver Wattle, Blue wattle, Mimosa.
Etymology: Acacia: From the Greek word ‘akakia’ meaning thorny Egyptian tree. dealbata: Whitened.
Origin: Native to New South Wales, Victoria, Australian Capital Territory and Tasmania. Naturalized in Adelaide, parts of south-west Western Australia and many other parts of the world, where in many cases, it has become a problem plant.
Description: Small to medium quick growing, bushy, elegant tree. Usually grows between 6-15m tall but can get as tall as 30m.
Foliage: Blue green to silvery grey on both surfaces, 4-10cm long, bipinnately divided into 8-26 pairs of leaflets, 25-40mm long. Each leaflet is further divided into 12-24 pairs of narrow linear to oblong leaflets 4-9mm long and 1-2mm wide.
Bark/Trunk: Smooth grey trunk, deeply fissured with age.
Flowers: Yellow to bright yellow 4-7.5mm diameter crowded on globase heads of 20-25 flowers grouped on long slender terminal or axillary panicles or racemes. Flowers from mid winter to spring, seeds hanging longitudinally .
Fruit: 3-10cm long by 5-14mm wide flat brown to black pods (straight or slightly curved).
Growth Requirements: Grows best in moist fertile soil but will tolerate a variety of conditions provided the soil isn’t permanently wet or waterlogged. It has also gained the Royal Horticultural Society’s Award of Garden Merit which basically means it can survive in Britain’s bleak conditions. Tree is short lived 30-40 years.
Uses: Bee, butterfly attracting, screen tree and for soil erosion control. It is also nitrogen fixing and is a good pioneer plant particularly in the regeneration of Mountain Ash (Eucalyptus regnans) forests. Other uses include being for its cut flowers and tips (widely used by florists in their designs), essence is used in perfumes, leaves are sometimes used in chutney and limited use as indoor timber,. More traditional uses by the Aboriginal people include using the timber for making stone axe handles and gum to fasten head. Gum was also eaten and used as a sweet drink.
Propagation: By seed or cutting. Seed can be viable for up to 50 years in the ground. Seeds generally require heating from bushfire to germinate so scarification of seed or leaving heating at 80 degrees Celsius for 5 minutes will improve germination significantly then plant to no more than 2mm deep. Seed will still germinate 30% of the time without assistance.
Sources of information:
- Australian trees by Leonard Cronin.
- Native splendour, Manningham City Council.
- Photography by Simon Schubert.