Acacia pachyacra
Acacia pachyacra
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 pachyacra is a plant of the hot, arid and semi-arid, subtropical to tropical zone of central Australia, where it is found at elevations up to 500 metres. It grows best in areas where annual daytime temperatures are within the range 12 - 30°c, but can tolerate 5 - 38°c[2]. When dormant, the plant can survive temperatures down to about -10°c, but young growth is more tender and can be severely damaged at -1°c[2]. It prefers a mean annual rainfall in the range 200 - 300mm, but tolerates 150 - 350mm[2]. Requires a sunny position in a well-drained soil[2]. Prefers a light to medium soil, which can be dry and of low fertility[2]. Found in the wild mainly on red-sand soils with a pH around 4.5 - 5.5[3]. Prefers a pH in the range 6 - 7, tolerating 5 - 8[2]. The species is short-lived and senesces rapidly within 5 years of establishment[3]. The plant has a potential for being a showy ornamental for arid inland areas on sandy soils[3]. Acacia seeds are highly nutritious and contain around 26% protein, 26% available carbohydrate, 32% fibre and 9% fat. The fat content is higher than most legumes with the aril providing the bulk of fatty acids present. These fatty acids are largely unsaturated. The energy content is high in all species tested, averaging 1480 ±270 kJ per 100g. The seeds are low glycaemic index foods - the starch is digested and absorbed very slowly, producing a small, but sustained rise in blood glucose and so delaying the onset of exhaustion in prolonged exercise[1]. 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[4]. 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[5]. A member of the ‘Acacia murrayana group’ with phyllodes very similar to those of Acacia subrigida . Perhaps Acacia pachyacra would be better regarded as a subspecies of Acacia murrayana from which it is (rather arbitrarily) distinguished by its narrower phyllodes[6].
Propagation
The seeds of this species usually germinate readily and often without the required dominancy breaking cues for germination[3]. The 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. 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[4]. Cite as: Tropical Plants Database, Ken Fern. tropical.theferns.info. 2026-02-19. <tropical.theferns.info/viewtropical.php?id=Acacia+pachyacra>
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]Ecocrop — http://ecocrop.fao.org/ecocrop/srv/en/home ↩︎Basic information on a wide range of useful plants, plus details of environmental needs where available.
- [3]Wattles of the Pilbara — http://worldwidewattle.com/speciesgallery/descriptions/pilbara/html/default.htm ↩︎A website with factsheets for the various Acacia species that grow in the Pilbara region of northwestern Western Australia
- [4]Potential of Australian Acacias in combating hunger in semi-arid lands — Rinaudo A.; Patel P.; Thomson L.A.J. · 2002 ↩︎
- [5]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.
- [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 ↩︎