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. Rigens from the Latin 'rigens' meaning stiff or rigid, referring to the stiff unbending needle-like phyllodes.
Distribution and status
Found in sandy alkaline yellow duplex, dark or grey-brown calcareous loamy earths, or brown calcareous earths on Eyre Peninsula, Yorke Peninsula, Mount Lofty Ranges, Flinders Ranges, Murray and the upper South-eastern. Also found in Western Australia, Queensland, New South Wales and Victoria. Native. Common in South Australia. Common in the other States.
Herbarium regions: North Western, Nullarbor, Gairdner-Torrens, Flinders Ranges, Eyre Peninsula, Northern Lofty, Murray, Yorke Peninsula, Southern Lofty, South Eastern
NRM regions: Adelaide and Mount Lofty Ranges, Alinytjara Wilurara, Eyre Peninsula, Northern and Yorke, South Australian Arid Lands, South Australian Murray-Darling Basin, South East
AVH map: SA distribution map (external link)
Erect, spreading, much-branched, glabrous or minutely hairy shrubs to 3 m high, sometimes developing a small tree-like form and attaining heights of 6 m. Leaves linear to 13 cm long and 2.5 mm wide. Inflorescences simple and axillary, solitary or twin, sometimes in clusters up to 4 heads with globular, mid-yellow flower-heads. Flowering between July and December. Fruits are long, curved, brown pods to 7 cm long and 3 mm wide. Seeds are dark brown ellipsoid seeds to 3 mm long and 2 mm wide. Seed embryo type is investing.
Seed collection and propagation
Collect seeds between November and December. 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. From one collection, the seed viability was average, at 50%. This species has physical dormancy that needs to be overcome for the seed to germinate (e.g. nicking or softening the seed coat).
|Location||No. of seeds|
|BGA||40,200 (112.6 g)||50||6-Dec-2005||DJD285|