Allocasuarina duncanii

Allocasuarina duncanii is a small, erect, dioecious tree that typically grows to a height of up to 8 m (26 ft). Its branchlets are up to 200 mm (7.9 in) long, the leaves reduced to scale-like teeth 0.8–1.5 mm (0.031–0.059 in) long, arranged in whorls of seven to nine around the branchlets. The sections of branchlet between the leaf whorls (the "articles") are 4–17 mm (0.16–0.67 in) long and 0.9–1.4 mm (0.035–0.055 in) wide. Male flowers are arranged in head-like spikes 7.5–13 mm (0.30–0.51 in) long, with six to eight whorls per centimetre (per 0.39 in.), the anthers about 1 mm (0.039 in) long. Female cones are cylindrical, on a peduncle 4–10 mm (0.16–0.39 in) long. Mature cones are 15–60 mm (0.59–2.36 in) long and 12–25 mm (0.47–0.98 in) in diameter, the samaras dark brown to black and 6–10 mm (0.24–0.39 in) long. This sheoak is similar to A. monilifera that is mostly monoecious, and lacks the "conifer-like" habit of A duncanii.

Duncan's sheoak grows in shallow soil over dolerite, usually at altitudes above 500 m (1,600 ft), on Mount Dromedary, the Wellington Range, Snug Tiers and on South Bruny Island.