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Acacia auriculiformis (Family Fabaceae)

Northern Black Wattle, Ear-pod Wattle

Distribution:

Natural stands are found in Australia, Papua New Guinea and Indonesia. In Australia it occurs on Cape York Peninsula and in the north of the Northern Territory. Its latitudinal range is 5-17o S and it is mainly found from near sea level to 100 m altitude (QLD, NT).

Features:

A fast-growing tree which on favourable sites can reach 30 m tall but is more commonly a smaller tree of 8-20 m. Young bark is smooth but it becomes rough and fissured with age. The phyllodes are straight or curved 8-20 cm long and about 1-4 cm wide. They have three prominent longitudinal nerves and a distinct gland at their base. The bright yellow flowers are in spikes up to 8 cm long. The pods are flat and rather woody about 7 cm long and up to 2 cm wide. As they mature they become very twisted and intertwined. The main flowering period is June-July and mature seed is found in September-October. It produces large quantities of seed at an early age and there are about 72 000 viable seeds per kilogram. Seeds need pre-treatment of boiling water for one minute to promote germination.

Ecology/Way of Life:

The natural occurrence is in hot, humid and sub-humid areas where there are no frosts. The annual rainfall range is mainly 1000-1500 mm mostly falling between December and March. In Australia this acacia grows on lateritic lowlands and coastal plains, frequently along river banks and drainage channels. It can grow on both sandy and clayey soils and tolerates waterlogging, high alkalinity and salinity. Few other species can match its ability to grow on harsh sites in the tropics. It is often the principal species in open forest along watercourses and in Papua New Guinea it is a component of swamp forest dominated by Melaleuca species.

Preferred Image

Interaction with Humans/Threats:

This fast growing tree has been widely planted for fuelwood production, erosion control, ornament and shade, especially in Asia but also in Africa and South America. It can be grown in industrial plantations to produce paper pulp and other timber products. Hybrids with Acacia mangium show great promise for this purpose in Vietnam. The heartwood is light brown to dark red and fine grained timber, so it makes attractive furniture. Young trees are easily damaged by fire and older trees coppice poorly. It seeds heavily and grows rapidly which suggest it has the potential to become a weed in some situations.

Other Comments:

Acacia auriculiformis was named in 1842 by explorer and botanist Allan Cunningham; the names are based on: the Greek akakia = a thorny plant, specifically Acacia arabica; Latin auricula = external ear of animal and forma = shape, referring to the shape of the seedpod.

Further Reading:

Boland, D.J., Brooker, M.I.H., Chippendale, G.M., Hall, N., Hyland, B.P.M., Kleinig, D.A., Johnston, R.D. and Turner, J.D. 1984. Forest trees of Australia. 4th ed. Nelson and CSIRO, Melbourne. 687p.

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.

Pinyopusarek, K. 1990. Acacia auriculiformis: an annotated bibliography. Winrock International and Australian Centre for International Agricultural Research. 154p.

Topics:

Climatic zones Soils Waterlogging Ornamental Commercial use Salt-tolerance Vegetation types Firewood Timber Agroforestry Nitrogen-fixation

Acknowledgments:

Text & map from Australian Trees and Shrubs, courtesy Australian Centre for International Agricultural Research; text edited by J. Turnbull; photo courtesy Maurice McDonald

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Sponsored by:

Maurice McDonald/ACIAR


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