Acacia aulacocarpa
Acacia aulacocarpa
Safety & Hazards
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
A tree of low to moderate elevations, it is mainly found in warm to hot humid and sub-humid zones of the tropics and subtropics, at the latitudinal range of 6 - 31°c[1]. It is able, however, to thrive in a range of climate conditions, succeeding in areas with a mean annual rainfall in the range of 500 - 3,000 mm and a mean annual temperature varying from a minimum of 10 - 21°c up to 29 - 38°c[1]. It can tolerate occasional mild frosts[1]. Succeeds in a range of soils from freely to imperfectly drained, usually acid or very acid and of low fertility[1]. It is found frequently on yellow soils, red or yellow podzolics that are usually acidic or very acid (pH 3.5 - 6) and of low fertility, and on sandy clay soils[1]. It tolerates a wide pH range[1]. The tree is cultivated as a source of timber outside its native range. In at least one region (the Cook Islands in the Pacific), it has escaped from cultivation and become established in the wild[2]. The main and lateral shoots grow almost throughout the year, but growth may stagnate during the very hot and dry season[1]. Trees can attain 12 - 16 metres in height and 11 - 14 cm in diameter in 4 years[1]. Trees generally start to flower after 3 years. The seeds mature 4 - 5 months after flowering and it is not unusual for the tree to produce 2 seed crops a year[1]. A spacing of 3 - 4 x 3 - 4 metres is considered suitable for firewood and pulpwood plantations[1]. The tree competes well with weeds, including Imperata cylindrica[1]. In plantations with 2 - 3 x 2 - 3 metres spacing, it will totally suppress the weed within 2 - 3 years[1]. However, weed control is necessary in the first 2 years to help establishment[1]. An 8 - 10-year rotation is recommended for pulpwood plantations, and a 15 - 20-year rotation for saw logs. The tendency of the tree to have a fluted stem may reduce its value for purposes such as veneer. Selection of a suitable provenance will be necessary to obtain optimum results[1]. Two varieties are recognised:- Var fruticosa is a bushy shrub growing up to 3 metres tall[1]. Var aulacocarpa is usually a tree 10 - 20 metres tall, but it ranges from a shrub of 4 metres on xeric sites to a large tree up to 40 metres tall in tropical rainforest[1]. 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[3].
Propagation
Seed - requires pre-treatment to break down the hard coat[1]. Pouring a small amount of boiling water over the seeds (which cools down quickly and so does not cook the seed), and then leaving to soak for 12 hours is usually effective, as is making a small incision in the coat to allow water to penetrate. Mature seeds germinate readily. Treated seeds are sown in germination beds, and seedlings are transplanted into polythene bags when they reach the 2-leaf-pair stage. Seeds can also be sown straight into polythene bags. Young seedlings should initially be kept at 50% sunlight, but this can be increased to 70% once they have been established. Excess shading often results in attack by mildew and other fungi in damping off. Adult foliage is reached about 6 weeks after germination[1]. In general, the seedlings are ready for transplanting 3 - 4 months after sowing[1]. 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]. Cuttings. Air layering. Cite as: Tropical Plants Database, Ken Fern. tropical.theferns.info. 2026-02-19. <tropical.theferns.info/viewtropical.php?id=Acacia+aulacocarpa>
Pollinators
Bees, Insects
References
- [1]World Agroforesty Centre — http://www.worldagroforestry.org/ ↩︎An excellent online database of a huge range of trees giving very good information on each plant - its uses, ecology, identity, propagation, pests etc.
- [2]Pacific Island Ecosystems at Risk — http://www.hear.org/pier/scientificnames/index.html ↩︎A very good website detailing weed species that have been introduced into the Pacific Islands.
- [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 Malesiana Series 1 — Various · Nationaal Herbarium Nederiand, Universiteit Leiden branch · http://www.archive.org ↩︎A massive treatment of the plants of the Malaysian Archipelago. Much of it has been made available to download from the Internet
- [6]Australian Native Plants Society — http://anpsa.org.au/index.html ↩︎A series of fact sheets on Australian plants. Good photographs, brief description and information on uses, habitat, range, cultivation etc.
- [7]IUCN Red List of Threatened Species — http://www.iucnredlist.org/ ↩︎A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.
- [8]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 ↩︎