Genoplesium ostrinum, commonly known as the purple midge orchid, is a species of small terrestrial orchid that is endemic to New South Wales. It has a single thin leaf and up to ten dark purple flowers with darker stripes and a hairy labellum which vibrates in the slightest breeze.
Genoplesium fimbriatum is a terrestrial, perennial, deciduous, herb with an underground tuber and a single thin leaf NaNsigfig=1NaNsigfig=1 long with the free part NaNsigfig=1NaNsigfig=1 long. Between three and ten dark purple flowers are crowded along a flowering stem NaNsigfig=1NaNsigfig=1 long and much taller than the leaf. The flowers are about 10sigfig=1NaNsigfig=1 long, 8.5sigfig=1NaNsigfig=1 wide and as with others in the genus, are inverted so that the labellum is above the column rather than below it. The dorsal sepal is 6sigfig=1NaNsigfig=1 long, 3sigfig=1NaNsigfig=1 wide with darker stripes, a pointed tip and hairy edges. The lateral sepals are 7.5sigfig=1NaNsigfig=1 long, 1sigfig=1NaNsigfig=1 wide with a humped base and spread widely apart from each other. The petals are 4sigfig=1NaNsigfig=1 long, 1.5sigfig=1NaNsigfig=1 wide and striped with hairy edges. The labellum is about 5sigfig=1NaNsigfig=1 long, 1.5sigfig=1NaNsigfig=1 wide with its tip curled upwards and long hairs on its edge. The labellum quivers in the slightest breeze. Flowering occurs between February and April.[1]
Genoplesium ostrinum was first formally described in 2001 by David Jones and the description was published in The Orchadian.[2] In 2002, Jones and Mark Clements changed the name to Corunastylis ostrina but the change is not accepted by the Australian Plant Census.[3] The specific epithet (ostrinum) is a Latin word meaning "purple".[4]
The purple midge orchid grows with shrubs or grasses in woodland between Tallong and Braidwood.