River Oak, River Sheoak, Creek Oak
This casuarina occurs from southern New South Wales to the Northern Territory. The subspecies cunninghamiana typically occurs along fresh water streams and rivers from southern new South Wales to northern Queensland; the subspecies miodon is found along larger rivers in the Northern Territory. The latitudinal range is 12-38o S and the altitudinal range from near sea level to 1000 m. (NT, QLD, NSW)Features:
A fast-growing, nitrogen-fixing, tall tree reaching 20-35 m in height and trunk diameter to 1.5 m. The subspecies miodon rarely exceeds 12 m in height and has a straggly appearance. The bark of this species is finely fissured, scaly and grey-brown. The deciduous branchlets are thin and soft and droop on vigorous trees. Tiny leaf-teeth occur in whorls of 8-10 in the subspecies cunninghamiana and 6-7 in the subspecies miodon. Male and female flowers occur on separate trees. Male flowers occur in terminal spikes at the tips of shoots and are arranged in whorls; female flowers are small, reddish and oval shaped; this species is wind pollinated. The woody cones, 7-14 mm long and 4-6 mm in diameter, comprise small, pale grey, winged, single seeded individual fruits, 3-4 mm long. The seeds mature in February - March in northern populations and slightly later in the south. There are about 600 000 viable seeds per kilogram and the seeds germinate readily without pre-treatment.Ecology/Way of Life:
This species is found mainly in the warm sub-humid climatic zones. Populations at higher altitudes in New South Wales tolerate up to 50 frosts per year and temperatures as low as -8o C but northern coastal localities are frost-free. Mean annual rainfall is 600-1100 mm although rainfall alone is no indication of the moisture available to the tree as it occurs along rivers. The soils are mainly acidic or near neutral sands or sandy loams. Casuarina cunninghamiana has a symbiotic relationship with nitrogen fixing bacteria Frankia which provides nitrogen to the tree and assists it to grow on soils of low fertility. River she-oak is generally the dominant species in riverbank vegetation and is usually replaced by C. glauca when the water becomes brackish in coastal rivers.Interaction with Humans/Threats:
It is used for windbreaks, shelterbelts, river bank stabilisation and as an ornamental and has been planted for these purposes in California, China, Egypt, New Zealand and elsewhere. The wood is strong, heavy, fine-textured, straight-grained and has wide rays. Its utilisation as sawn wood is limited by its tendency to warp, twist and split during seasoning. However, it makes an excellent fuel and was once favoured for heating bakers' ovens. The foliage is a useful drought fodder but does not have high nutritive value. The species provides valuable supplies of pollen for bees.Other Comments:
Casuarina cunninghamiana was described by Friedrich Miquel (1811-1871) in 1848, in memory of Allan Cunningham (1791-1839), an explorer and botanical collector. 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. There are two subspecies: cunninghamiana and miodon; the latter based on the Greek mio= less or little and odontos = tooth, referring to the smaller leaf-teeth in this form.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.
Midgley, S.J., Turnbull, J.W. and Johnston, R.D. (eds.) 1983. Casuarina ecology, management and utilization. CSIRO, Melbourne. 286p.
Wilson, K.L. and Johnson, L.A.S. 1989. Casuarinaceae. Flora of Australia: 3: 100-189.Australian Government Publishing Service, Canberra.Topics: Climatic zones Windbreak Ornamental Firewood Plant structure Soils Fodder Timber Germination Aboriginal resources Nitrogen-fixation
Text & map from Australian Trees and Shrubs, courtesy Australian Centre for International Agricultural Research; text edited by J. Turnbull; photo courtesy M. McDonald.Sponsored by: