Acacia pycnantha Benth.

Mimosaceae

Common name(s):

Golden wattle, Broad-leaved wattle (New South Wales), South Australian Golden wattle (South Australia)

Description:

Bushy shrub, 4-6 m high or small tree reaching up to 10 m in height and 30 cm in diameter. Heights of 12 m are recorded from Morocco (Reafforestation Hand-book of Morocco, 1978). The bark is grey and glossy and thickens with age. The twigs are glaucous. Leaves of 8-20 x 2-3.5 cm, falcate, dark green with a conspicuous principal vein; phyllodinous.  Inflorescence in glomerules, bright-yellow, 0.8-1.0 cm in diameter, forming long clusters. Very handsome in blossom, hence the name of “golden wattle” and the specific name of “pycnantha”, which means “dense flowers”. Pods of 8-13 cm x 0.5 cm flattened, slightly constricted between the seeds which are black and shining.

Distribution:

The species is a native to South Australia, south of the Flinders Range, to a large part of the State of Victoria with moderate rains, and to New South Wales in the areas bordering the two former states. It has been cultivated extensively since the mid-19^th century and became acclimatized all over Victoria, except in the Australian Alps and the most arid parts in the north-west and in the central and southern coastal zones of New South Wales, including the regions of Sidney and Blue Mountains.  It was introduced to India and Morocco where it is believed it can replace A. cyanophylla in some sites, since it has a better habit and contains more tannin. It is sensitive to calcium carbonate and tends to become chlorotic in soils with a high lime content. It prefers siliceous sands and stony hills. Young plants are sensitive to frost.  The species has a reputation of drought resistance, as demonstrated by the beautiful individual trees that grow, without irrigation, at Broken Hill (Australia). It needs 370-550 mm in the cool season and can withstand very hot and very dry summers.  In Morocco, this species is adequate for semi-arid to humid climates, in their warm to cool variants.

Propagation:

Establishment by sowing of seeds, pre-treated in boiling water, in the nursery is no problem. However, there is little further planting in Australia owing to competition from other tanning products.

Management:

Stands can be totally exploited for the tanning bark from about the age of 7-10 years.

Products and uses:

After having been used for a long time for its tanning bark (up to 40% of tanning and more), Acacia pycnantha has come to be considered an ornamental tree, by reason of its glowing blossom, as well as a producer of fuel wood. However, it may still have an interest in some rural communities for tanning. The wood is used in turnery. It may be used in ornamental avenues or as a shade tree for livestock. It may also be used in conjunction with Eucalyptus cladocalyx, the “sugar gum”, to create double-storey wind-breaks, since the Eucalyptus reaches 20-30 m in height. It is a species with a high pollen production that honey bees highly appreciate when the air is humid, for instance close to a water pool, to the sea-shore or in case of dew. Otherwise the pollen becomes too dry and bees cannot harvest it.

Main References:

Baumer, M. 1983. Notes on Trees and Shrubs in Arid and Semi-arid Regions. FAO/UNEP programme “Ecological Management of Arid and Semi-Arid Rangelands in Africa, Near and Middle East” (EMASAR Phase II). 270p.