Prasophyllum mimulum is a terrestrial,
perennial,
deciduous,
herb with an underground
tuber and a single tube-shaped leaf which is long and wide. Between three and ten greenish-brown to purplish flowers are well-spaced along a flowering spike which is long reaching to a height of . The flowers are wide and as with other leek orchids, are inverted so that the
labellum is above the
column rather than below it. The
dorsal sepal is long and wide and the
lateral sepals are long and wide. The petals are purple with white edges and are long, wide. The labellum is white, long, wide, and turns sharply upwards through more than 90° near its middle. There is a yellowish green
callus in the centre of the labellum and extending just past the bend. Flowering occurs from January to March. ==Taxonomy and naming==