Coast Sheoak, Beach Casuarina, Shingle Oak, Beach Sheoak, Horse-tail Sheoak
The subspecies equisetifolia occurs naturally on tropical coastlines from northern Australia through much of south-east Asia and the Pacific. In Australia, it is found in a narrow coastal strip from Darwin in the Northern Territory to near Cairns in northern Queensland. The subspecies incana extends southwards from central Queensland to near Port Macquarie, New South Wales and is also found in Vanuatu and New Caledonia. The species has a latitudinal range of 20o N-31o S and an altitudinal range from sea level to 100 m. (NT, QLD, NSW)
In Australia, subsp. equisetifolia is usually a small tree, 8-16 m tall, but in some other countries it it is a tall,, straight tree that can reach a height of 35 m and a diameter of 50 cm. Subsp. incana is typically a small tree or large shrub 6-10 m tall. The crown is finely branched and the branchlets are drooping, needle-like, 20-40 cm long and sometimes hairy. The minute teeth-like reduced leaves are whorls of 7-8. Most trees bear both male and female flowers. Male flowers occur on simple, terminal, elongated spikes 7-40 mm long and arranged in whorls. Female flowers are on lateral, woody branches. It is wind pollinated. The cones, 10-24 mm long and 9-13 mm in diameter, comprise small, dull brown, winged and single seeded individual fruits, 3-4 mm long. There are about 270 000 viable seeds per kilogram and the seeds germinate readily without pre-treatment.
Ecology/Way of Life:
The subspecies equisetifolia occurs in hot humid to sub-humid areas while the subspecies incana is in the warm sub-humid zone. The area is frost-free. In Australia, the mean annual rainfall is 1000-1700 mm with a strong monsoonal pattern in the north. Coast she-oak is commonly confined to a narrow strip on sandy coasts and rarely extends inland. It is subject to salt spray and occasionally to inundation with seawater. Soils are principally deep, well-drained and course-textured sands which may be alkaline. It has a symbiotic relationship with the nitrogen-fixing actinomycete bacteria Frankia which assists it to grow on low fertility soils. This species may be the only woody plant on the coastal sand dunes growing over grasses and broad-leaved herbs, or it can be part of a richer association of trees and shrubs.
Interaction with Humans/Threats:
Coast she-oak's most common use is for sand dune stabilisation, shelterbelts, land reclamation and erosion control. It has been extensively planted for these purposes in China, India, Vietnam and West Africa. The wood is hard and heavy and makes good firewood and charcoal. It is not easy to saw but it is used in the round as posts, poles and piles, and has been used as raw material for paper and rayon production. Root extracts have been used for treating stomach disorders. It has become a weed in Hawaii and Florida.
Casuarina equisetifolia was first described in 1759. 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 is named from the Latin equinus = of horses, and folium = leaf, referring to the fine drooping twigs which are reminiscent of horse hair. There are two subspecies: equisetifolia and incana.
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. and House, A.P.N. 1993. Casuarina: an annotated bibliography of C. equisetifolia, C. junghuhniana and C. oligodon. International Council for Research in Agroforestry (ICRAF), Nairobi. 298p.
Pinyopusarek, K., Turnbull, J.W and Midgley, S.J. (eds.). 1996. Recent casuarina research and development. CSIRO Forestry and Forest Products, Canberra. 247p.
Wilson, K.L. and Johnson, L.A.S. 1989. Casuarinaceae. Flora of Australia: 3:100-189.
Topics:Agroforestry Salt-tolerance Salinity issues Windbreak Soil Conservation Firewood Climatic zones Vegetation types Timber Aboriginal resources Medical use Plant structure Pollination Nitrogen-fixation Soil Conservation
Text & map from Australian Trees and Shrubs, courtesy Australian Centre for International Agricultural Research; text edited by J. Turnbull; photo courtesy M. McDonald
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