Genoplesium pumilum is a terrestrial, perennial, deciduous, herb with an underground tuber and a single thin leaf 100–200 mm (4–8 in) long and fused to the flowering stem with the free part 10–20 mm (0.4–0.8 in) long.

[2][3][4] The green midge orchid was first formally described in 1853 by Joseph Dalton Hooker who gave it the name Prasophyllum pumilum and published the description in Flora Novae-Zelandiae.

In Tasmania it grows on buttongrass plains and in New Zealand on sparsely vegetated gumland scrub.

In New South Wales it occurs mainly in coastal districts and in Victoria in the far east and on French Island.

It is also common in coastal areas of Tasmania and in New Zealand is found on the North and Chatham Islands.