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A Floridata Plant Profile #731 Casuarina equisetifolia
Common Names: Australian pine, horsetail casuarina, she-oak, horsetail tree, beefwood, Polynesian ironwood
Family: Casuarinaceae (casuarina Family)
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tree  Fast Growing Drought Tolerant Has Medicinal Uses Has evergreen foliage

Australian pine
Australian pine is often seen along canals and bordering fields in southern Florida where it was once planted for quick growing windbreaks.
Description
Australian pine is a large vase-shaped tree that grows 100-150 ft (30.5-45.7 m) in height with wispy grey green twigs reminiscent of pine needles. The weeping branchlets look a little like jointed rushes and are ringed at their nodes by tightly overlapping little scalelike leaves. The stout trunk is covered with thick pebbly textured brownish grey bark. The tree is supported by a dense, spreading, fibrous root system. The male flowers are borne in slender cylindrical spikes at the twig tips. The tiny brownish red female flowers grow in heads attached to the branchlets and are followed by 0.5 in (1.3 cm) diameter fruits that resemble pinecones and contain 70-90 winged seeds each. Australian pine produces minor quantities of fruit constantly, but it usually goes through two major blooming and fruiting cycles each year. In Florida, there is a peak bloom period in April and a secondary one in September, with the largest numbers of seed becoming available in June and December. Australian pine often grows 5-10 ft (1.5-3.1 m) per year and has been known to reach 30 ft (9.1 m) in two years. In Florida, the usual life span of an Australian pine is 40-50 years, but there are reports that they can live hundreds of years in parts of their native range.

Australian pine trunk and bark
Location
Australian pine is native from Southeast Asia to northern Australia and the Pacific, but it has been planted and has naturalized on beaches, berms, and similar open coastal sites in tropical areas throughout the world. In its native region, Australian pine occurs in habitats ranging from subtropical thorn scrubland to wet forest. The trees grow best in slightly uneven topography where holes and swales hold rainwater reserves. Recently disturbed places like cleared vacant lots and filled wetlands are ideal.

Australian pine twigs
It's not really a pine and these are not needles - the "foliage" of Australian pine actually consists of wispy thin green twigs.
Culture
Australian pine prefers sandy soils, but saline, calcareous, rocky, volcanic, granitic, or just plain poor soils are all okay. The pH can be anywhere between 5.0 and 7.7. Since this species forms symbiotic nitrogen-fixing associations with soil microbes, it can grow on nearly sterile sands, though it does appreciate fertilizer. It even seems tolerant of some types of soil pollution, occurring around cement plants and on tin mine tailings. The trees respond well to pruning and can be shaped into a hedge. Grafting is also feasible and it is possible that grafting non-seeding species of Casuarina onto the non-suckering C. equisetifolia rootstock might yield an acceptable non-invasive plant for salt barrier hedges. Australian pine is very sensitive to fire, and may be killed by even a light burn. Young trees have trouble competing with grasses, but they have been reported to survive in the company of cogongrass (Imperata cylindrica), which is one of the world's most aggressive weeds.
Light: Australian pine demands full sun.
Moisture: 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.
Hardiness: USDA Zones 9 - 11. Australian pine loves hot weather! It dislikes long cold periods, suffers from frost and dies when the temperature drops to between 18 to 26ºF (-7.7 - -3.9ºC).
Propagation: Trees begin producing seed when they are only 3-5 years old. Mature specimens yield prodigious quantities of seed, of which 30-80 percent can be expected to germinate 4-8 days after planting. Seeds usually remain viable for only a few months, though they may survive up to two years under ideal conditions. The winged seeds are usually wind dispersed, but the "cones" float and can be transported by water. They may also be spread by birds, especially parrots and parakeets. Some Casuarina species form thickets of root sprouts, but this one rarely suckers.

Australian pine
Australian pines along the Rickenbacker Causeway in Miami, Florida frame condominium towers rising along Biscayne Bay.
Usage
Australian pine is extremely salt resistant and is often used as a windbreak or barrier or to provide beachfront shade or privacy. It may also be trimmed into a hedge or dwarfed in the greenhouse as a bonsai tree. The trees are widely cultivated for erosion control and soil nitrification. The pulp has been used to make paper. The wood is so exceptionally hard, strong, and heavy that it often bends sawblades and nails. It is durable in saltwater, but it is very susceptible to drywood termites, rots easily, and resists wood preservatives. It is brittle and prone to crack, split and shrink. It is nevertheless used for fenceposts, poles, beams, pilings, and the like. Australian pine makes an outstanding fuelwood and is recommended for biomass energy plantations. The wood has been used for powering locomotives and firing brick kilns.

Except for maybe jellyfish, the Australian pine "cones" are a bare foot's worst worry when visiting South Florida beaches.
A decoction from the astringent bark has been used as a remedy for diarrhea, beri-beri, sore throat, cough, headache, toothache, sores, and swellings. Extracts from the bark are also used for tanning hides and staining and preserving fishing lines and fabrics. The wood ash has been used to make soap. The "cones" are used in novelties for the tourist trade.

Features
If you live in a primitive country where fuelwood is in high demand and you have an overworked old farm field that needs rejuvenation and stabilization, plant a stand of Australian pine. There's not much excuse for anybody else growing this troublesome weed. But what do you do if you already have one? You could wait for a storm to blow it over on top of your house. Or you could have a barbecue! Australian pine is regarded as the world's best firewood. Cut your tree down and burn it. Just remember that Australian pine isn't called ironwood for nothing; cut it up into firewood before it gets so dry and hard it wrecks your saw. If you cut it low enough, the roots may die, but Casuarinas are notorious for resprouting, so it would be wise to paint the fresh stump with brushkiller.

WARNING
This is a destructive invasive species! Australian pine is an extremely aggressive and densely rooted species that smothers its struggling competitors under a heavy blanket of needle-like litter. Monocultural stands displace sand-binding native dune and beach vegetation, encouraging coastal erosion, changing soil chemistry, degrading wildlife habitat, and drastically altering coastal environments. Few animals can survive in the ecologically sterile interior of an Australian pine forest. The Plant Conservation Alliance names this species as an Alien Invader. It is listed as a Category I invasive exotic species by the Florida Exotic Pest Plant Council. This means that it is known to be "invading and disrupting native plant communities in Florida". Possession, collection, transportation, cultivation and importation of Australian pine are prohibited by the Florida Department of Environmental Protection.

If you decide to keep your Australian pine, be forewarned that these trees are shallow-rooted and highly susceptible to windthrow in severe storms. Specimens thus overturned open the soil to erosion and thereby accelerate rates of beach loss. The trees also shed hard pointed "cones" that make walking barefoot under them an unpleasant experience. And, Casuarina pollen can cause allergic reactions such as respiratory problems, eye irritation, rhinitis, and/or hoarseness.

Linda Conway Duever 7/15/00; updated 11/07/00, 6/18/04





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