Plants of
South Australia
Acacia rigens
Leguminosae
Needlebush Wattle
Display all 19 images
Regional Species Conservation Assessments per IBRA subregion.
Least concern
Near threatened
Rare
Vulnerable
Endangered
Critically endangered
Extinct
Data deficient
Adelaide
Arkaroola
Ceduna
Coober Pedy
Hawker
Innamincka
Marla
Marree
Mount Gambier
Oodnadatta
Renmark
Wudinna
Keith
Yunta
Enlarge Map
Copy Map
Copy Map
Display IBRA region text

Botanical art

Kath Alcock paintings: 9.

Etymology

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)

Plant description

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).

Seeds stored:
  Hide
LocationNo. of seeds
(weight grams)
Number
of plants
Date
collected
Collection number
Collection location
Date
stored
% ViabilityStorage
temperature
BGA40,200 (112.6 g)506-Dec-2005DJD285
Eyre Peninsula
1-Aug-200650%-18°C
Location: BGA — the seeds are stored at the Adelaide Botanic Gardens, MSB — the seeds are stored at the Millennium Seed Bank, Kew, England.
Number of plants: This is the number of plants from which the seeds were collected.
Collection location: The Herbarium of South Australia's region name.
% Viability: Percentage of filled healthy seeds determined by a cut test or x-ray.