Diuris ostrina, commonly known as Darling Scarp donkey orchid, is a species of orchid that is endemic to the south-west of Western Australia. It has two or three linear to lance-shaped leaves and up to five brown to brownish-yellow and purple-mauve flowers.
Diuris ostrina is a tuberous, perennial herb with two or three linear leaves long and wide. Up to five brown to brownish-yellow and purple-mauve flowers long and wide are borne on a flowering stem tall. The dorsal sepal is egg-shaped, long and wide, the lateral sepals narrowly oblong, parallel or crossed, long and wide. The petals are broadly elliptic, long and wide on a stalk long. The labellum is long with three lobes - the centre lobe broadly wedge-shaped, long and wide, the side lobes spread widely apart and egg-shaped to oblong, long and wide. There is a single smooth, yellow callus ridge long, along the mid-line of the labellum. Flowering occurs in October and November.[1] [2]
Diuris ostrina was first formally described in 2016 by David Jones and Christopher J. French in Australian Orchid Review, from a specimen collected in Greenmount National Park in 1997.[3] The specific epithet (ostrina) means "purple", referring to the main colour of the labellum of this species.[4]
Darling Scarp donkey orchid is restricted to the Darling Scarp where it grows in shrubby forest and woodland in the Jarrah Forest and Swan Coastal Plain bioregions of south-western Western Australia.
Diuris ostrina is listed as "not threatened" by the Western Australian Government Department of Biodiversity, Conservation and Attractions.