Prostanthera decussata, commonly known as dense mintbush,[2] species of flowering plant that is endemic south-eastern Australia.

It is a dense, compact, strongly aromatic shrub with egg-shaped leaves and mauve to violet flowers with yellow streaks, arranged in leaf axils near the ends of branchlets.

Prostanthera decussata is a dense, compact, strongly aromatic shrub that typically grows to a height of up to 2 m (6 ft 7 in).

[2][3] This species was formally described in 1859 by Victorian Government Botanist Ferdinand von Mueller in Fragmenta phytographiae Australiae, based on plant material collected in mountainous country near the Macalister River in Victoria.

[6] Dense mintbush grows in heath, forest and woodland in the eastern half of Victoria, in the Australian Capital Territory and mainly in the south-eastern part of New South Wales.