Australian blackwood

Appearance

The tree is able to grow to a height of around 20 m and has a bole that is approximately 150 cm in diameter. It has deeply fissured, dark-grey to black coloured bark that appears quite scaly on older trees. It has angular and ribbed branches The bark on older trunks is dark greyish-black in colour, deeply fissured and somewhat scaly.

Younger branches are glabrous, ribbed and angular to flattened near the greenish coloured tips. The stems of younger plants are occasionally hairy. Like most species of "Acacia" it has phyllodes rather than true leaves. The glabrous, glossy, leathery, dark green to greyish-green phyllodes have a length of 4 to 16 cm and a width of 6 to 30 mm with a variable shape. They most often have a narrowly elliptic to lanceolate shape and are straight to slightly curved and often taper near the base and have three to five prominent longitudinal veins.

In its native area it blooms between July and December producing inflorescences that appear in groups to two to eight on an axillary raceme, the spherical flower-heads have a diameter of 5 to 10 mm and contain 30 to 50 densely packed pale yellow to nearly white coloured flowers.

Following flowering smooth, firmly papery and glabrous seed pods form. The curved or twisted or coiled pod have a biconvex shape with a length of 4 to 12 cm and a width of 5 to 8 mm and contain longitudinally arranged seeds.Sapwood may range in colour from straw to grey-white with clear demarcation from the heartwood. The heartwood is golden to dark brown with chocolate growth rings. The timber is generally straight grained but may be wavy or interlocked. Quartersawn surfaces may produce an attractive fiddleback figure. The wood is lustrous and possesses a fine to medium texture.

Naming

The species is also known as Blackwood, hickory, mudgerabah, Tasmanian blackwood, or blackwood acacia.
The name of the wood may refer to dark stains on the hands of woodworkers, caused by the high levels of tannin in the timber.

Distribution

In its native range the tree is found down the east coast of Australia from Queensland in the north, down the east coast into New South Wales, through Victoria and west along the south coast of South Australia. It is also found down the east coast of Tasmania.

Status

It has been introduced to many countries for forestry plantings and as an ornamental tree. It now is present in Africa, Asia, Europe, Indian Ocean, the Pacific Ocean, South America and the United States. It is a declared noxious weed species in South Africa and is a pest in Portugal's Azores Islands. It was also recently listed by the California Invasive Plant Council as an invasive weed that may cause limited impact. Its use as a street tree is being phased out in some locales because of the damage it often causes to pavements and underground plumbing. In some regions of Tasmania, blackwood is now considered a pest.