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. Oswaldii named after Ferdinand Oswald, a former resident of Adelaide and later returning home to Germany, who was involved with the collection of the type specimen with Ferdinand von Mueller in 1851 near Blanchetown, South Australia.
Distribution and status
Found scattered across South Australia except on Kangaroo Island and the South-East, growing in open woodland or tall shrubland on calcareous loamy or sandy soils. Also found in all mainland states. Native. Common in South Australia. Common in the other States.
Herbarium regions: North Western, Lake Eyre, Nullarbor, Gairdner-Torrens, Flinders Ranges, Eastern, Eyre Peninsula, Northern Lofty, Murray, Yorke Peninsula, Southern Lofty, Green Adelaide
NRM regions: Adelaide and Mount Lofty Ranges, Alinytjara Wilurara, Eyre Peninsula, Northern and Yorke, South Australian Arid Lands, South Australian Murray-Darling Basin
AVH map: SA distribution map (external link)
Dense, rounded, spreading shrubs or small trees to 6 m high with bushy umbrella-liked canopy with finely fissured, rough, dark grey bark. Leaves linear, oblong-lanceolate to 8 cm long and 1 cm wide, flat, thick, rigid, striate, silvery or somewhat golden pubescent when young, becoming glabrous with age, with numerous fine parallel more or less prominent veins and straight or curved pungent tip. Inflorescences in axil with 1 or 2 pale yellow golbular flower-heads. Flowering irregularly throughout the year but mainly between October and January. Fruits are linear pod to 17 cm long and 10 mm wide, spirally twisted, leathery to woody. Seeds are black, glossy, hard, globular to ovoid to 7 mm along and 6 mm wide with a broad fleshy, yellowish-orange aril. Seed embryo type is investing.
Seed collection and propagation
Collect seeds between January to April. 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).