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Casuarina glauca (Family Casuarinaceae)

Swamp Sheoak, Swamp Oak, Grey Swamp Sheoak

Distribution:

This casuarina is restricted to a narrow coastal belt in eastern Australia, from central Queensland to southern New South Wales. The latitudinal range is 23-37o S and the main occurrence is from sea level to 25 m above sea level. (QLD, NSW)

Features:

A fast-growing, nitrogen fixing tree 8-20 m tall that frequently regenerates by vigorous suckers. The bark is grey brown, hard and with a blocky appearance. The foliage is bluish-green and the segments are 8-20 mm long with tiny leaf teeth in whorls of 12-17. Male flowers occur in spikes 1-4 cm long and the female flowers are usually reddish and hairy. The mature woody cones are cylindrical, 9-18 mm long and comprise pale coloured winged seeds 3.5-5 mm long. Mature seed may be collected over several months. There are about 400 000 viable seeds per kilogram. They germinate readily without pre-treatment and store well. Like other casuarinas, it has an actinomycete bacterium (Frankia) which forms nodules on its roots and fixes nitrogen from the atmosphere.

Ecology/Way of Life:

This she-oak grows in the warm humid and sub-humid zones. The area near the coast is frost-free but a few light frosts may occur inland each year. Mean annual rainfall is 900-1700 mm with a well-defined summer-autumn maximum in the south and a strong summer maximum in the north. It typically grows on swampy flats, near estuaries and along tidal reaches of rivers and on river terraces. The soils are usually poorly drained humic gleys. This casuarina is often found in pure stands or associated with melaleucas, such as Melaleuca quinquenervia, in woodland associations. The stands are often adjacent to tall eucalypt forest including Eucalyptus botryoides, E. robusta and E. tereticornis.

Interaction with Humans/Threats:

The heartwood is brownish, has prominent rays, and is hard, heavy and tough. It splits easily. It was formerly used in Australia for shingles, tool handles, fence rails and small piles for saltwater. Wood from trees grown in Egypt has proved suitable for making particle board. An excellent tree for amenity planting and shelterbelts. Its tolerance to periodic waterlogging, salt spray and highly saline soils makes it suitable for sand dune stabilisation and land reclamation, especially in coastal or salt-affected situations. It can become a weed under some circumstances.

Other Comments:

Casuarina glaucawas named in 1826 by Franz Sieber from Czechoslovakia who made plant collections in New South Wales in 1823. The genus name is based on the Malay kasuari = the cassowary, referring to the resemblance of the tree's foliage to the cassowary's plumage. The species name is from the Greek glaukos = bluish-green, referring to the colour of the foliage.

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.

Marcar, N.E. Crawford, D.F., Leppert, P.L., Jovanovic, T., Floyd, R. and Farrow, R. 1995. Trees for saltland. A guide to selecting native species for Australia. CSIRO, Melbourne. 72p.

Topics: Climatic zones Firewood Germination Plant structure Salt-tolerance Fodder Timber Aboriginal resources Nitrogen-fixation Vegetation types Fodder

Acknowledgments:

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

Sponsored by:

Tim Vercoe/ACIAR


 

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