Genoplesium arrectum, commonly known as the erect midge orchid and as Corunastylis arrecta in Australia, is a small terrestrial orchid endemic to south-eastern Australia. It has a single thin leaf fused to the flowering stem and up to twenty small, dark purple flowers. It grows in a montane and subalpine grassland and forest in Victoria and the Australian Capital Territory.
Genoplesium arrectum is a terrestrial, perennial, deciduous, herb with an underground tuber and a single thin leaf NaNsigfig=1NaNsigfig=1 long and fused to the flowering stem with the free part NaNsigfig=1NaNsigfig=1 long. Between three and twenty dark purple flowers are crowded along a flowering stem NaNsigfig=1NaNsigfig=1 tall and taller than the leaf. The flowers are about 6sigfig=1NaNsigfig=1 long, 3sigfig=1NaNsigfig=1 wide and are inverted so that the labellum is above the column rather than below it. The dorsal sepal is a broad egg shape, about 4sigfig=1NaNsigfig=1 long and 2.5sigfig=1NaNsigfig=1 wide with hairless edges and dark coloured bands. The lateral sepals are linear to lance-shaped, about 5sigfig=1NaNsigfig=1 long, 1sigfig=1NaNsigfig=1 wide, stiffly erect and more or less parallel to each other. The petals are a narrow egg shape, about 3.5sigfig=1NaNsigfig=1 long and 1sigfig=1NaNsigfig=1 wide with dark coloured bands and hairless edges. The labellum is elliptic to broadly egg-shaped, about 3sigfig=1NaNsigfig=1 long, 2sigfig=1NaNsigfig=1 wide, thick and fleshy with coarse hairs on its edges. There is an narrow egg-shaped callus in the centre of the labellum and extending three-quarters of the way to its tip. Flowering occurs in December and January.[1] [2]
Genoplesium arrectum was first formally described in 1991 by David Jones from a specimen collected near Omeo and the description was published in Australian Orchid Research.[3] [4] In 2002 Jones and Mark Clements changed the name to Corunastylis arrecta.[5] The specific epithet (arrecta) is a Latin word meaning "upright",[6] referring to the stiffly erect lateral sepals.
Genoplesium arrectum grows in grassland and grassy forest at altitudes above 900sigfig=1NaNsigfig=1 in north-eastern Victoria and in the Australian Capital Territory.