Northern Kurrajong, Tropical Kurrajong, Airitja, Nanunguwa
This species has an extensive distribution in northern Australia. The subspecies diversifolius occurs in the Kimberley region of Western Australia and the northern part of the Northern Territory while subspecies orientalis grows in north Queensland. The latitudinal range is 11-19o S and the altitudinal range mainly from near sea level to 200 m but with subsp. orientalis extending to 500 m. (QLD, NT, WA)
A fast-growing, deciduous to semi-deciduous, small tree, 5-18 m tall and a cylindrical trunk up to 35 cm diameter. The leaves are oval or, rarely, heart-shaped, 6-18 cm long by 3-10 cm wide, shiny above, and grow on a leaf stalk 3-8 cm long. The small male and female flowers do not have true petals but the calyx is petal-like and is green blotched with red inside and golden brown hairs outside. They form clusters of 15-60 flowers. The dark grey to black fruits are woody cases (follicles) which split open when ripe and reveal yellow or cream seeds amongst prickly hairs. These hairs may irritate the skin. Flowering and fruiting times vary but mature fruits are usually available October-December. Differences between the subspecies were described by Guymer in 1988.
Ecology/Way of Life:
In coastal areas this species occurs in sub-humid and hot, humid zones while inland it extends into the hot, semi-arid zone. Mean annual rainfall is 440-1500 mm with a strong summer maximum. The area is frost-free. The topography is usually flat or undulating but it does occur on low tablelands and coastal sand dunes. It occurs mainly as scattered individuals in woodlands and open-forests dominated by eucalypts such as Eucalyptus miniata and E. tetrodonta. It is also found in deciduous woodlands dominated by Terminalia spp. and vine thickets.
Interaction with Humans/Threats:
The wood is light and soft, and not very durable. It is not used for timber and probably would be a poor fuelwood. The leaves are eaten by sheep and cattle. It is used for shelterbelts and as a shade tree. Aboriginal people used it for many purposes. The seeds are nutritious and were eaten raw or roasted. Roots of young plants were also eaten raw or cooked. Firesticks and spears were made from the wood and string from the bark. The leaves, bark and gum were used as medicines to treat skin wounds and fevers, and an extract from the inner bark was used as an eye wash.
Brachychiton diversifolius was named in 1844 by the Scottish botanist, Robert Brown, who accompanied Matthew Flinders' expedition to Australia in 1801; Brown wrote the first systematic account of the Australian flora; the genus Brachychiton is formed from the Greek brachys = short; and chiton = outer covering, indicating the loose outer covering of the seed; the species name comes from the Latin diversus = different, and folium = leaf, because of the variation in size and shape of the juvenile leaves; there are two subspecies - subsp. diversifolius and subsp. orientalis from the east.
Aboriginal Communities of the Northern Territory. 1993. Traditional Aboriginal medicines in the Northern Territory of Australia. Conservation Commission of the NT. Government Printer, Darwin.
Brock, J. 2001. Native plants of northern Australia. Reed New Holland, Sydney.
Doran, J.C. and Turnbull, J.W. (eds.) 1997. Australian trees and shrubs; species for land rehabilitation and farm planting in the tropics. ACIAR Monograph no. 24. Australian Centre for International Agricultural Research, Canberra. 384p.
Guymer, G.P. 1988. A taxonomic revision of Brachychiton (Sterculiaceae). Australian Systematic Botany 1: 228-231.
Topics:Aboriginal resources Fodder Plant structure Climatic zones Soils Vegetation types Firewood Timber
Text & map from Australian Trees and Shrubs, courtesy Australian Centre for International Agricultural Research; text edited by J. Turnbull; photo courtesy David Lea.
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