Common name: Burdekin plum

Burdekin Plum or Tulip Plum is an Australian native fruit tree occurring in subtropical and tropical areas on the east coast of the country.

It is a highly variable species in both form and fruit quality, ranging from shrubs to medium-sized trees and with fruit that may be very sour through to pleasantly sub-acid, depending on the variety and growing conditions.

In cultivation, and under good growing conditions, it develops into a small to medium-sized tree, 15 to 20 m (15 to 65 ft) tall with a stout trunk supporting an irregularly shaped crown. The bark on mature trees dark grey and fissured.

The leaves are large and compound, made up of four to eight glossy green oval leaflets arranged in pairs along the length and with an extra leaflet at the tip. They emerge bronze-red and remain on the plant throughout the year.

The flowers are small and insignificant, creamy-white to pale yellow and with male and female flowers held in separate, loosely formed clusters on the same plant. They bloom in spring and are followed by plum-sized fruit, 3 to 4 cm (1 to 1.5 in) in diameter, with a squat pumpkin-shape ripening to dark purple or near black from late summer to autumn.

The fruit pulp, though thin, is juicy, either purple, greenish-white or a cross between those two colours and clings to a large dimpled seed.

Use

The fruit are best stored a few days after harvest, to allow the flesh to soften and lose some of its astringency. The best quality fruit have a sourish to sub-acid, mildly resinous flavour and can be eaten fresh out-of-hand, though are more commonly into jam or jelly.

Burdekin plum produces a heavy wood, averaging out at over 900 kgs per cubic meter (56 lbs per cubic ft), with dark reddish-brown heartwood. However, the logs come in small diameters, which makes sawing them into lumber impractical. The wood is used mostly in its roundwood form and is suitable for wood-turning, usually for making tool handles, walking sticks, umbrella handles and similar articles.

The fallen fruit and seed are part of the natural diet of native wildlife, particularly the Cassowary, a large flightless bird indigenous to the tropical rainforests of the region.

Climate

Grows naturally in sub-humid to moderately humid subtropical and tropical lowland to mid-elevation climates, generally areas with annual lows of 15 to 24°C, annual highs of 27 to 33°C, annual rainfall of 700 to 2000 mm and a dry season of 3 to 7 months. However, Burdekin plum reaches its best development in areas with annual rainfall of 1200 mm or more.

Growing

New plants are usually grown from seed, which benefit from soaking in warm water overnight before sowing.

Burdekin Plum performs best on rich, free-draining loam, sandy-loam and loamy-sand soils of a moderately acid to neutral nature, generally with a pH of 5.0 to 7.0, and on sites with full to partial sun exposure.

Problem features

There does not appear to be any record of it as a weed anywhere in the world.

Books

• Barwick, M., et al. 2004, Tropical & subtropical trees : a worldwide encyclopaedic guide, Thames and Hudson, London

• Bristow, M. & Bragg, A. & Annandale. M. 2005, Growing rainforest timber trees: a farm forestry manual for north Queensland, Research and Development Corporation (RIRDC), Barton, A.C.T, Australia

• Doran, J. C & Turnbull, J. W. 1997, Australian trees and shrubs : species for land rehabilitation and farm planting in the tropics, 2nd ed, Australian Centre for International Agricultural Research (ACIAR), Canberra, Australian Capital Territory

• Hall, N. 1972, The use of trees and shrubs in the dry country of Australia, Australian Government Publishing Service, Canberra, Australian Capital Territory

• Lake, M. 2015, Australian rainforest woods : characteristics, uses and identification, CSIRO Publishing, Collingwood, Victoria

• Lyle, Susanna 2006, Discovering fruit & nuts : a comprehensive guide to the cultivation, uses and health benefits of over 300 food-producing plants, David Bateman, Auckland, N.Z

• Martin, F. M., et al. 1987, Perennial edible fruits of the tropics : an inventory, U.S. Dept. of Agriculture (USDA), Agricultural Research Service, U.S. Government Printing Office (GPO), Washington, D.C.

• Randall, R. P. 2007, The introduced flora of Australia and its weed status, Cooperative Research Centre for Australian Weed Management, Glen Osmond, South Australia

• Wickens, G. E 1995, Edible nuts, Food and Agriculture Organization of the United Nations (FAO), Rome