Acacia difficilis
Acacia difficilis
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 difficilis is a plant of semi-arid to moist tropical climates in northern Australia, where it is found at elevations up to 200 metres. It grows best in areas where annual daytime temperatures are within the range 22 - 35°c, but can tolerate 13 - 42°c[2]. When dormant, the plant can survive temperatures down to about 2°c, but young growth is more tender and can be severely damaged at 2°c[2]. It prefers a mean annual rainfall in the range 650 - 1,100mm, but tolerates 450 - 1,500mm[2]. Requires a sunny position. Found in the wild on light to medium-textured soils, preferably well-drained, and tolerating low fertility[2]. Plants are tolerant of short periods with the soil inundated[2]. Prefers a pH in the range 5 - 6.5, tolerating 4.5 - 7[2]. A fast-growing tree (sometimes more than 2 metres a year when young) with a moderate life-span of 10 - 50 years. It produces seed heavily early in its life - flowering can commence before the tree is 12 months old[3]. 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]. The seedpods of this species split open elastically at maturity, making the seed difficult to harvest, but the seed is more easily cleaned than for other Acacia species[3]. Plants do not always respond well to coppicing, especially when cut very low[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[2]. Acacia difficilis is allied to, and often confused with, Acacia tumida. The two are difficult to distinguish in herbarium material in the absence of pods[5].
Propagation
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+difficilis>
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]Australian Trees and Shrubs: Species for Land Rehabilitation and Farm Planting in the Tropics — Doran J.C.; Turnbull J.W. (Editors) · Australian Centre for International Agricultural Research; Canbe · 1997 · ISBN 1-86320-127-0 ↩︎A very informative book, rich in information about the uses, cultivation needs and very much more for over 160 species of Australian trees and shrubs.
- [4]Potential of Australian Acacias in combating hunger in semi-arid lands — Rinaudo A.; Patel P.; Thomson L.A.J. · 2002 ↩︎
- [5]Flora of Australia — http://www.anbg.gov.au/abrs/abif/flora/ ↩︎The full information from the Flora of Australia - on-line. An excellent resource.
- [6]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 ↩︎