Prostanthera petrophila is a species of flowering plant in the family Lamiaceae and is endemic to Western Australia. It is a spreading shrub with densely hairy branches, narrow egg-shaped leaves with the narrower end towards the base and white flowers with violet striations in the petal tube.
Prostanthera petrophila is a spreading shrub that typically grows to a height of and has densely hairy branches. The leaves are more or less glabrous, narrow egg-shaped with the narrower end towards the base, long and wide on a short petiole. The flowers are arranged in groups of about ten to sixteen on the ends of branchlets, each flower on a pedicel long. The sepals form a tube long with two lobes, the lower lobe long and the upper lobe long. The petals are white with violet striations in the tube and on the lobes, long and form a tube long. The lower lip of the petal tube has three lobes, the centre lobe spatula-shaped, long and the side lobes long. The upper lip is long, wide with a central notch deep. Flowering occurs in August.[1]
Prostanthera petrophila was first formally described in 1988 by Barry Conn in the journal Nuytsia from specimens collected near Mount Barloweerie in 1931.[2]
This mintbush grows on laterite and in rock crevices in the Murchison and Yalgoo biogeographic regions of Western Australia.
Prostanthera petrophila is classified as "Priority Three" by the Government of Western Australia Department of Parks and Wildlife meaning that it is poorly known and known from only a few locations but is not under imminent threat.[3]