It is a monoecious shrub with its leaves reduced to overlapping scales in whorls of nine to eleven, the mature fruiting cones 10–23 mm (0.39–0.91 in) long, containing winged seeds 5.5–7.0 mm (0.22–0.28 in) long.

Male flowers are arranged in spikes 15–30 mm (0.59–1.18 in) long, with seven or eight whorls per centimetre (per 0.39 in.

[2][3] This sheoak was first formally described in 1923 by Charles Gardner who gave it the name Casuarina spinosissima in the Journal and Proceedings of the Royal Society of Western Australia from specimens he collected near Carrabin in 1922.

[8] Allocasuarina spinosissima grows in heath on sandplains and is widespread between Southern Cross, Norseman and Queen Victoria Spring in the Avon Wheatbelt, Coolgardie, Esperance Plains, Great Victoria Desert, Mallee and Murchison Coastal Plain bioregions of Western Australia.

[3][2] Allocasuarina spinosissima is listed as "not threatened" by the Western Australian Government Department of Biodiversity, Conservation and Attractions.