The she-oaks (genera Casuarina and Allocasuarina) may not be particularly spectacular but they have their place in the Australian landscape. Because of the needle-like leaves they have the appearance of a conifer with attractive vertical lines.
The she-oak family has the scientific name of Casuarinaceae. In 1982, the Casuarina genus was divided into four. The true Casuarina has about 17 species, six of which are confined to Australia. The Malay Archipelago and the Pacific Islands are home to the rest. The genus Allocasuarina has 59 species, all of which are endemic to Australia.
The Allocasuarinas are similar to conifers in appearance. Although they appear to have no leaves, the leaves are actually fused flat against the surface of the twigs. The tips remain free and look like rings of tiny teeth appearing at regular intervals along the twig. In most cases, male and female flowers are borne on different plants. The fruits are held in a cone-like spike. When conditions are right, these burst apart releasing small winged nuts which bear the seeds. To propagate this genus, the seed can be gathered from cones and the germination is almost assured.
Allocasuarina littoralis is also known as the Black She-oak and comes from the east coast of Australia. It grows to 8m and is a slender tree with fine foliage and dark-grey fissured bark. Rusty brown, male flower spikes are produced in March through to May followed by small red female flowers. It is adaptable to a wide range of well-drained situations. It was previously known as Casuarina littoralis. It is suited to exposed coastal positions and is frost-hardy.
The Dwarf She-oak (Allocasuarina pusilla) is bushy and, as its name implies, only grows to 3 metres. It has deep red male flowers, seen from March to October. It will grow in clay or sandy soils.
Allocasuarina verticillata (Drooping She-oak) is an attractive tree (11 metres), often found on coastal cliffs in the wild. It is bushy with a short, erect trunk and rounded, weeping crown. The bark is dark and furrowed. Yellow-brown male flowers are produced during March to December. It prefers a well-drained site but tolerates wet periods. It was previously known as Casuarina stricta
Allocasuarina decussata (9 metres) has a low-branching bushy habit and is endemic to south-west Western Australia. The branches are slender and the branchlets a fine-textured, rich green. In winter, male flowers appear covering the tips of the branches with reddish brown anthers.
Allocasuarinas are tough and hardy. They are suited to poor soils, including sandy, stony and relatively infertile conditions. The taller species will adapt to more fertile soils.
She-oaks are part of the typical Australian landscape.