Allocasuarina pusilla, commonly known as heath oak-bush[1] or dwarf sheoak,[2] is a species of flowering plant in the family Casuarinaceae and is endemic to south-eastern continental Australia. It is a spreading, dioecious shrub with branchlets up to long, the leaves reduced to scales in whorls of five to seven, the fruiting cones long containing winged seeds about long.
Allocasuarina pusilla is a spreading, dioecious shrub that typically grows to a height of and has smooth bark. Its branchlets are erect to spreading, up to long, the leaves reduced to overlapping, scale-like teeth long, arranged in whorls of five to seven around the branchlets. The sections of branchlet between the leaf whorls are long and wide. Male flowers are arranged in spikes long, with about 8 to 11 whorls per centimetre (per 0.39 in.), the anthers long. Female cones are sessile, the mature cones shortly cylindrical to more or less spherical, long and in diameter, the winged seeds dark brown to black and about long.[3]
This sheoak was first formally described in 1927 by Ellen Dulcie Macklin who gave it the name Casuarina pusilla in the Transactions and Proceedings of the Royal Society of South Australia.[4] [5] It was reclassified in 1982 as Allocasuarina pusilla by Lawrie Johnson in the Journal of the Adelaide Botanic Gardens.[6] The specific epithet (pusilla) means "very small",[7] possibly referring to the habit of the plant.
Allocasuarina pusilla grows in heath on sandy soils from the Yorke Peninsula in south-eastern South Australia to the Big and Little Deserts of western Victoria in the south-east of continental Australia.