The swamp oak is a moderately fast-growing, evergreen tree that can reach a height of around 18 metres with a bole up to 60cm in diameter.
Valued for its wood and its ability to stabilize and reclaim soil, the tree has been widely planted outside of its native country. It has proved to be superior to many other species under Mediterranean type climates and many difficult sites. However, it should be used with some care since it has the potential to become weedy.
Casuarina glauca, commonly known as the swamp she-oak, swamp oak, grey oak, or river oak, is a species of Casuarina native to the east coast of Australia. It is found from central Queensland south to southern New South Wales. It has become naturalised in the Everglades in Florida where it is considered a weed.
The swamp oak grows as medium sized tree, 8–20 m high tree, or rarely over 30 m tall. It can be restricted to a stunted shrub around 2 m (7 ft) tall when exposed to the elements on clifftops. The greyish brown bark has scales and small fissures. The branches have numerous drooping branchlets that are up to 38 cm long, and composed of small cylindrical segments known as articles. These articles are 8 to 20 mm long and 0.9–1.2 mm wide. The leaves themselves are reduced to tiny 'teeth' that are 0.6 to 0.9 mm long. 12–17 (rarely 20) teeth arise from the nodes between articles on the branchlets. The oval cones are 9–18 mm long by 7–9 mm wide.
The plant suckers freely and forms a good windbreak. It has a rapid colonizing ability on disturbed soils, especially in coastal or salt affected situations.
The low ranching habit and extensive litter production help reduce soil erosion. It has been used to reclaim land, especially eroded mountainsides, to stabilize dunes and streambanks, and to provide shelterbelts. The plant can spread very freely by means of suckers and has become a noxious weed in some areas - its planting is banned in some parts of Florida. Ditches are sometimes dug on either side of the shelterbelt planting in order to control its spread.