Genoplesium woollsii, commonly known as dark midge-orchid, is a species of orchid endemic to New South Wales. It has a single thin, wiry leaf and in autumn has up to thirty five drooping, dark purple flowers on a flowering stem which is fused to the lower part of the leaf.
Genoplesium woollsii is a terrestrial, perennial, deciduous, sympodial herb with a single cylindrical, leaf fused to the flowering stem. The leaf is long and the free part is long and ends below the flowers. Between five and thirty five dark purple flowers with darker streaks are arranged on a flowering stem tall. The flowers droop forwards, and are about long, wide. As with others in the genus the flowers are inverted so that the labellum is above the column rather than below it. The sepal is egg-shaped, long, wide, sharply pointed and with short hairs on the edges. The sepals are linear to lance-shaped, long, wide and diverge from each other. The petals are egg-shaped, long, about wide with a pointed tip and short hairs on the edges. The labellum is egg-shaped, long, wide with densely hairy edges and a sharply pointed tip. There is a callus in the centre of the labellum and along about three-quarters of its length. Flowering usually occurs between February and April.
The dark midge orchid was first formally described in 1865 by Ferdinand von Mueller who gave it the name Prasophyllum woollsii and published the description in Fragmenta phytographiae Australiae'. In 1989, David Jones and Mark Clements changed the name to Genoplesium woollsii.
Dark midge-orchid grows in heath, forest and moss gardens mainly between the Blue Mountains and Batemans Bay.