Genoplesium formosum, commonly known as the Cathcart midge orchid, is a small terrestrial orchid found in southern New South Wales. It has a single thin leaf and up to twenty five dark reddish purple flowers with darker lines.
Genoplesium formosum 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 ten and twenty relatively large flowers are crowded along a flowering stem NaNsigfig=1NaNsigfig=1 tall and slightly taller than the leaf. The flowers lean downwards, are dark reddish purple with darker lines and are NaNsigfig=1NaNsigfig=1 long and NaNsigfig=2NaNsigfig=2 wide. As with others in the genus, the flowers are inverted so that the labellum is above the column rather than below it. The dorsal sepal is NaNsigfig=2NaNsigfig=2 long, NaNsigfig=2NaNsigfig=2 wide with a sharply pointed tip. The lateral sepals are NaNsigfig=2NaNsigfig=2 long, NaNsigfig=1NaNsigfig=1 wide with a pointed tip and are free from each other. The petals are NaNsigfig=1NaNsigfig=1 long, about 2sigfig=1NaNsigfig=1 wide and have a pointed tip and sometimes a few hairs on the edges. The labellum is egg-shaped with the narrower end towards the base, thick and fleshy, NaNsigfig=2NaNsigfig=2 long, NaNsigfig=2NaNsigfig=2 wide with a sharply pointed tip and coarse hairs on its edges. There is a callus in the centre of the labellum and extending nearly to its tip. Flowering occurs between October and December.[1]
Genoplesium formosum was first formally described in 2001 by David Jones from a specimen collected in the Wadbilliga National Park and the description was published in The Orchadian.[2] In 2002 Jones and Mark Clements changed the name to Corunastylis formosa but the change is not accepted by the Australian Plant Census.[3] The specific epithet (formosum) is a Latin word meaning “beautifully formed” or "handsome".[4]
The Cathcart midge orchid grows with shrubs or grasses near streams or near swamps. It is found in isolated populations between Wadbilliga National Park and Cathcart.