Acacia rivalis
Acacia rivalis
Safety & Hazards
The seed of many Acacia species, including this one, is edible and highly nutritious, and can be eaten safely as a fairly major part of the diet. Not all species are edible, however, and some can contain moderate levels of toxins[1]. Especially when harvesting from the wild, especial care should be taken to ensure correct identification of any plants harvested for food[PFAF]. Especially in times of drought, many Acacia species can concentrate high levels of the toxin Hydrogen cyanide in their foliage, making them dangerous for herbivores to eat.
Cultivation Details
Acacia rivalis is a native to the semi-arid and arid regions of temperate southern Australia, where it can be found at elevations up to 750 metres. It grows best in areas where the mean maximum temperature of the hottest months can reach 30 - 35°c, and the mean minimum in the coldest month can fall to 2 - 5°c. The plant can experience moderate frosts, down to around -5°c for short periods. Mean annual rainfall can vary from 150 - 400mm, with a dry season of 3 - 12 months[2]. Requires a sunny position and a well-drained soil[2]. The plant has a moderate to fast rate of growth, though it is relatively short-lived with a life span of probably 15 - 20 years[2]. In one trial site on a clay soil plants were around 2 metres tall when two years old[2]. Plants do not sucker, and only coppice weakly, but regenerates abundantly by seed following fire[2]. The seedpods ripen over about a year, maturing between mid Spring and early Summer. Ripening oods and flowers are often found together on the same plant. The plant can produce large quantities of seed[2]. The seeds of most acacia species can be quickly and efficiently harvested at full maturity without the need for any specialised equipment. Small seed-bearing branches can be cut and beaten on sheets, or bushes can be beaten or shaken directly onto large sheets[3]. This species has a symbiotic relationship with certain soil bacteria; these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[4].
Propagation
Seed - best sown as soon as it is ripe in a sunny position in a warm greenhouse[5].The dried seed of most, if not all, members of this genus has a hard seedcoat and may benefit from scarification before sowing to speed up germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (being careful not to damage the embryo) and soak for a further 12 hours before sowing. Sow the seed in Spring in a greenhouse. As soon as the seedlings are large enough to handle, prick them out into individual pots and grow them on in a sunny position in the greenhouse for their first winter. Plant them out in late spring or early summer, after the last expected frosts, and consider giving them some protection from the cold for their first winter outdoors. Acacia seeds that have matured fully on the bush and have been properly dried have a hard seed coat and can be stored in closed containers without deterioration for 5 - 10 years or more in dry conditions at ambient temperatures. It is best to remove the aril, which attracts weevils and can lead to moulds forming. The arils are easilyremoved by placing the seeds in water and rubbing them between the hands, then drying the seeds and winnowing them[3]. Cite as: Temperate Plants Database, Ken Fern. temperate.theferns.info. 2026-02-20. <temperate.theferns.info/plant/Acacia+rivalis>
Pollinators
Insects
References
- [1]Acacia in Australia: Ethnobotany and Potential Food Crop — Lister P.R.; Holford P.; Haigh T.; Morrison D.A. · ASHS Press, Alexandria, VA. · 1996 · https://hort.purdue.edu/newcrop/proceedings1996/v3-toc.html · ISBN 0-9615027-3-8 ↩︎
- [2]Acacia Search; Evaluation of Acacia as a woody crop option for Southern Australia — Maslin B.R. & McDonald M.W. · Rural Industries Research and Development Corporation; Western A · 2004 · ISBN 0642 58585 7 ↩︎
- [3]Potential of Australian Acacias in combating hunger in semi-arid lands — Rinaudo A.; Patel P.; Thomson L.A.J. · 2002 ↩︎
- [4]Nodulation Plants in GRIN Taxonomy — United States Department of Agriculture · http://www.ars-grin.gov/~sbmljw/cgi-bin/taxnodul.pl?language=en ↩︎An online database listing plants that have either positive or negative reports on root and stem nodulation with nitrogen-fixing bacteria.
- [5]RHS Dictionary of Plants plus Supplement. 1956 — F. Chittendon. · Oxford University Press · 1951 · ISBN - ↩︎Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaced in 1992 by a new dictionary (see [ 200 ]).
- [6]Flora of Australia — http://www.anbg.gov.au/abrs/abif/flora/ ↩︎The full information from the Flora of Australia - on-line. An excellent resource.
- [7]The Useful Native Plants of Australia. — Maiden J.H. · Turner & Co.; London. · 1889 · http://www.biodiversitylibrary.org ↩︎Terse details of the uses of many Australian plants and other species naturalised, or at least growing, in Australia. It can be downloaded from the Internet.
- [PFAF]Plants for a Future — pfaf.org ↩︎