Macadamia Nut, Queensland Nut, Smooth-shelled Macadamia, Bush Nut, Nut Oak
This species occurs in south-east Queensland, where it overlaps with M. tetraphylla in the south of its range. The latitudinal range is 25-28o S; the main altitudinal distribution is 400-600 m and the range 10-1000 m. (QLD)
A bushy tree to 20 m tall with a slightly rough, brown bark. The shiny mature leaves are 10-30 cm long by 2-4 cm wide, in whorls of three. The small, white flowers are borne in spring in long pendulous clusters. The globular fruits are up to 35 mm in diameter, green at first and brown at maturity. They have a hard outer covering and also a hard inner shell which encloses the seed. Fruits ripen in March-June.
Ecology/Way of Life:
The climate is warm, sub-humid or humid and macadamias can withstand mild frosts. Mean annual rainfall is 1100-1700 mm with a summer maximum. It is found on sub-coastal low hills, rocky slopes and headlands near the coast, protected valleys of coastal rivers and offshore islands. Soils are well-drained, fertile, red loams or alluvials. Much of their natural habitat has been cleared but scattered individuals occur in coastal rainforest and in fringing rainforest along creeks.
Interaction with Humans/Threats:
Macadamias produces highly nutritious, edible nuts. Hawaiian selection of trees have dominated plantings but higher yielding Australian selections are now used. They are propagated by budding and grafting and a light crop can be harvested 4-5 years after planting. Each tree will produce 35 kg of nuts in shell at maturity and orchards have a productive life of 20-40 years. It also makes an attractive ornamental and shade tree although trees are prone to wind damage on exposed sites.
Macadamia integrifolia was named in 1897 by Joseph Maiden and Ernest Betche; the genus name honours J. Macadam (1827-65), Secretary of the Philosophical Institute in Victoria; the species name is from the Latin integri = whole, and folium = leaf, referring to the entire (smooth) margins of the adult leaf. It is closely related to Macadamia tetraphylla.
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.
Holliday, I. 1989. A field guide to Australian trees. Hamlyn Australia, Port Melbourne. 320p.
Stephenson, R.A. and Winks, C.W. 1992. Macadamia integrifolia. In: Verjeij, E.W.N. and Coronel, R.E. (eds.) Edible fruits and nuts, 195-198. Plant Resources of Southeast Asia no. 2. PROSEA, Bogor, Indonesia.
Topics:Ornamental Soils Vegetation types Oil production Commercial use Human food production Timber
Text & map from Australian Trees and Shrubs, courtesy Australian Centre for International Agricultural Research; text edited by J. Turnbull; photo courtesy R. Loebel.
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