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| Common Name: |
Australian River Oak |
| Scientific Name: |
Casuarina cunninghamiana |
| Hardiness Zone: |
9B through 11 |
| Family: |
Casuarinaceae |
General Information
Early promoters of Casuarina species in Florida envisioned a wide variety of applications, including hardwood, pulpwood, and tannin, as well as the abundant sprouts serving as a source of forage for cattle. Casuarinas have proven inadequate for every one of these applications, although there have been reports of the tannin being used for curing alligator skins and preserving fishing lines. While cattle readily eat the sprouts in Australia, they are recognized as high in tannin, astringent, and constipating, and are used for hardship fare only. It is now known that tannin interferes with digestive system utilization of protein, results in weight deficits, and is carcinogenic. Although hard, heavy, and strong, with a fine texture and tightly interlocked grain, the wood is brittle, difficult to plane smooth, and prone to crack and split. Seasoning results in heavy and uneven shrinkage, severe cupping, surface checking, casehardening, and other defects. The logs are difficult to saw; saws tend to heat, chatter, and veer off course producing offsize timber with little market value. This tree does not commonly form root suckers, as does the Casuarina glauca. Although reportedly durable in salt water, the wood is very susceptible to drywood termites and not long-lasting in the ground (Vietmeyer 1986). The most widely agreed upon and valuable application of Casuarina appears to be as firewood, especially in third world countries such as India and China. While reportedly difficult to start burning, it will burn when green and the ashes retain heat for a long time. It has a calorific value of 4,950 cals., 8,910 Btu's and has been called "the best firewood in the world"
Basic Care
| Bark Characteristics: |
The bark is hard and thick, light to dark gray. |
| Leaf/Foliage Characteristics: |
The 7-10 leaf teeth are sharply pointed, mostly appressed with a narrow, brown, central portion and a gray tip. |
| Growth Characteristics |
Casuarina cunninghamiana is the hardiest of the Casuarinas; it is found mostly in the central to northern regions of Florida where it has been known to survive temperatures as low as -8.8° C. C. cunninghamiana's poor tolerance of salt spray and salt water inundation limits distribution along beaches. |
| Flower/Fruit Characteristics: |
The cones are small, as long as wide, with thin glabrous, bracteoles. The samaras are 3-5 mm long; dull gray-brown. |
| Lighting: |
Full Sun. |
| Watering: |
Young trees need deep watering during dry spells. Established specimens are drought tolerant but will shed branchlets when stressed from lack of water. They don't mind soggy soils and wet feet, but resent prolonged flooding. |
| Feeding: |
Use a well balance fertilizer such as 20-20-20. |
| Pruning/Wiring: |
The tree lends itself to weeping, slanting and cascade styles. As the needles grow longer, pinch them back. Due to the speed with which the tree grows, this pinching can take place as often as once a month. |
| Propagation: |
Seeds, or cuttings of half-ripened wood. |
| Potting: |
Australian Pines can be repotted every 2-3 years, night tempertures should be a minimum of 55 degrees. |
| Pests: |
In Florida, wood borers may attack the Australian Pine. The Lymantriid moth, Lymantria xylina, is one of the worst pests of Casuarina equisetifolia and C. glauca in China (Li et al. 1981). Ants have been a major source of control in both Puerto Rico and India probably explaining why Casuarina has not over-run Puerto Rico as it has started to do in Florida. Nursery seedlings in India are attacked by Brachytrupes achatinus (cricket), Arbela tetraonis (a bark-eating caterpillar), Coelosterna scabrata (a longicorn) and the grubs of Oryctes rhinoceros (the rhinoceros beetle). . |
| Diseases: |
Blister disease caused by Trichosporium visiculosum Butler is fast spreading and may wipe out Casuarina from Hyderabad and other parts of Andhra Pradesh in India (Begum and Rizwana 1979). This root fungus is encouraged by excessive watering and crowding (Morton 1980). There has been a high rate of root rot in Florida Casuarinas caused by Clitocybe tabescens (Rhoads 1952). This has occurred primarily on higher, well-drained, light sandy soils where oak and other hardwood trees were predominant before clearing. This fungus is known to attack 210 species of plants belonging to 137 genera and 59 families. Stem canker and die-back attributable to the fungus Diplodia natalensis have affected trees in Puerto Rico. |
| Bibliography: |
USDA, NRCS. 2009. The PLANTS Database (http://plants.usda.gov). National Plant Data Center, Baton Rouge, L A 70874-4490 USA. Edward F. Gilman, associate professor, Environmental Horticulture Department; Dennis G. Watson, associate professor, Agricultural Engineering Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville FL 32611. Casuarina equisetifolia, Susan C. Elfers, Global Invasive Species Team, The Nature Conservancy. Australian Pine, Erik Wigert, Wigert's Bonsai Nursery, North Ft Myers, Florida (www.wigertsbonsai.com). |
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