Leionema microphyllum, commonly known as limestone phebalium, is a small shrub with terminal clusters of white-pink flowers in spring.

Leionema microphyllum is a small shrub to 40 cm (16 in) high with terete branchlets that are covered with tiny star-shaped hairs or sometimes smooth.

The stiff, leathery leaves are egg-shaped to broader egg-shaped, 3–5 mm (0.12–0.20 in) long, 2–4 mm (0.079–0.157 in) wide with an apex almost heart-shaped or pointed to rounded, occasionally smooth or with minute star-shaped hairs with flat, smooth margins.

The dry fruit are smooth, about 4 mm (0.16 in) high and the surface finely corrugated with a rounded apex.

[6] This species has a restricted distribution in Victoria growing in heathland in the Natimuk district, but unknown in the area since 1962, and found near Lake Hindmarsh in 2014.