Pterostylis erubescens, commonly known as the red sepaled snail orchid, is a species of orchid endemic to the south-west of Western Australia. Non-flowering plants have a rosette of leaves flat on the ground but flowering plants lack a rosette and have a single large green flower which turns reddish-brown as it ages, and has leaves on the flowering spike.
Pterostylis erubescens is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette of leaves NaNsigfig=1NaNsigfig=1 in diameter. Flowering plants have a single green flower NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide on a flowering stem NaNsigfig=1NaNsigfig=1 high. The flowers turn reddish-brown as they age. There are up to ten leaves NaNsigfig=1NaNsigfig=1 long and NaNsigfig=2NaNsigfig=2 wide on the flowering stem. The dorsal sepal and petals are fused, forming a hood or "galea" over the column, the dorsal sepal with a tapered tip and the petals broadly flared. The lateral sepals are held close to the galea, almost close off the front of the flower and have erect, thread-like tips NaNsigfig=1NaNsigfig=1 long. The labellum is relatively large but not visible from outside the flower. Flowering occurs from late July to September.[1]
Pterostylis erubescens was first formally described in 2014 by David Jones and Christopher French from a specimen collected near Augusta and the description was published in Australian Orchid Review. The species had previously been known as Pterostylis sp. 'red flowered'.[2] The specific epithet (erubescens) is a Latin word meaning "reddening" referring to the colour of the upper parts of the flowers of this species.
The red sepaled snail orchid grows in forest, woodland and around granite outcrops between Mandurah and Albany in the Esperance Plains, Jarrah Forest, Swan Coastal Plain and Warren biogeographic regions.
Pterostylis erubescens is listed as "not threatened" by the Government of Western Australia Department of Parks and Wildlife.