Allocasuarina robusta, commonly known as Mount Compass oak-bush,[1] is a species of flowering plant in the family Casuarinaceae and is endemic to a restricted area of South Australia. It is a monoecious, rarely a dioecious shrub with erect 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 robusta is a monoecious, rarely a dioecious shrub that typically grows to a height of and has smooth bark. Its branchlets are more or less erect, up to long, the leaves reduced to 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 5 to 9 whorls per centimetre (per 0.39 in.), the anthers long. Female cones are sessile or on a peduncle up to long, the mature cones cylindrical, long and in diameter, the winged seeds black and long.[2] [3]
Mount Compass oak-bush was first formally described in 1927 by Ellen Dulcie Macklin who gave it the name Casuarina paludosa var. robusta 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 (robusta) means "hard" or "robust".[7]
Allocasuarina robusta grows in heath and heathy woodland at higher elevations in an area of in the southern Mount Lofty Ranges, on the Fleurieu Peninsula to the south of Adelaide.
Allocasuarina robusta is listed as "endangered" under the Australian Government Environment Protection and Biodiversity Conservation Act 1999. The main threats to the species include vegetation clearing, grazing pressure, road maintenance activities and weed invasion.[8]