Family: Casuarinaceae
Common Name: She-oak

This genus now comprises only 12 species, the remainder having been transferred to the genus Allocasuarina. Many are native to Australia, though some are found in the South Pacific and the islands to the north of Australia. These evergreen trees have weeping, needle-like branchlets, the true leaves being the tiny scale-like formations at the junctions of the branchlets. The flowers are inconspicuous and are followed by woody cones of variable shape and size. Fast-growing, they are useful as windbreaks, and as shade and amenity trees, and some make excellent soil binders. Different species are useful for different soil and climatic conditions, including coastal headlands, swamps and river banks.

Species

Widely planted in warm regions including California and Florida.

C. cristata, belah, to 12 m (40 it), is drought-resistant and makes an ideal windbreak or decorative tree for arid areas. It has gray-green foliage.

C. cunninghamiana, river oak, is the largest of the species and grows to 20-30 m (65-100 ft) in favorable conditions. Fast-growing, it is useful as a shade and shelter tree, but is particularly useful for stabilizing soils on river banks. It must have ample summer water but is tolerant of several degrees of frost.

C. equisetifolia, horsetail tree, can grow to 5-10 m (16-33 ft), depending on the conditions prevalent. It can tolerate strong, salty winds and poor soils, although on exposed sites its growth can be stunted. It has no tolerance for frost. This species has been widely planted in coastal areas of China where its timber is used in a variety of ways.

C. glauca, swamp oak, occurs naturally along tidal estuaries in eastern Australia. It has a very upright growth habit, to 15-20 m (50-65 ft), and under sheltered conditions can spread as wide as 5 or 6 m (16-20 ft). It does best in deep, good quality soil, with ample water.

Cultivation

In areas subject to frosts, grow as young plants in pots or tubs in a cool greenhouse or conservatory, using soil-based potting compost, and provide maximum light. Outdoors, casuarinas prefer an open, sunny position. All species, except C. glauca, which thrives in swampy ground, like quite well drained soil. Propagation is from seed sown in spring.

Climate

Zones 9 and 10 are suitable.