Acacia from the Greek 'akakia' and derived from 'ake' or 'akis' meaning a sharp point or thorn and 'akazo' meaning to sharpen. Dioscorides, the Greek physician and botanist used the word in the 1st century AD for the Egyptian thorn tree, Acacia arabica. Mearnsii named after Colonel Edgar Alexander Mearns (1856 - 1916), an American who collected the type from a cultivated specimen in East Africa.
Distribution and status
Found growing naturally in the lower South-east and naturalise on the lower Eyre Peninsula and in the Mount Lofty Ranges in South Australia, growing in woodland, open forest and tussock grassland on leached sand with a hardpan and loam. Also found in New South Wales, Victoria and Tasmania and introduced to Western Australia. Native and introduced. Common in South Australia. Common in the other States.
Herbarium regions: Eyre Peninsula, Southern Lofty, South Eastern, Green Adelaide
NRM regions: Adelaide and Mount Lofty Ranges, Eyre Peninsula, South East
AVH map: SA distribution map (external link)
Small, spreading trees to 10 m high with a rounded or conical canopy and branches almost to the ground. Bark of main trunk blackish and round, often exuding gum, young branches smooth and greenish-brown. Leaves bipinnate and softly pubescent with 1 gland at base of paired leaves. The presence of glands at the junction of, as well as between, the pinna pairs distinguishes this species from Acacia dealbata. Inflorescences on long, axillary racemes and panicles with pale yellow globular flower-heads. Flowering between September and November. Fruits broad-linear pod to 10 cm long and 8 mm wide, dark grey-brown to blackish covered with a fine whitish hairs. Seed embryo type is investing.
Seed collection and propagation
Collect seeds between December and February. Collect mature pods that are turning brown, with hard, dark seeds inside. Place the pods in a tray and leave to dry for 1-2 weeks or until the pods begin to split. Then rub the dried pods to dislodge the seeds. Use a sieve to separate any unwanted material. Store the seeds with a desiccant such as dried silica beads or dry rice, in an air tight container in a cool and dry place. This species has physical dormancy that needs to be overcome for the seed to germinate (e.g. nicking or softening the seed coat).