Pterostylis platypetala, commonly known as the broad-petalled snail orchid, is a species of orchid endemic to the south-west of Western Australia. It has a rosette of leaves and when flowering, a single green and white flower with relatively wide petals. In ideal conditions it can form colonies of hundreds of plants and often grows under melaleucas on the edge of winter-wet areas.
Pterostylis platypetala is a terrestrial, perennial, deciduous, herb with an underground tuber. It has a leaf rosette NaNsigfig=1NaNsigfig=1 in diameter. Flowering plants have a single green and white flower NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide on a flowering stem NaNsigfig=1NaNsigfig=1 high. There are three or four stem leaves NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide with their bases wrapped around the flowering stem. The dorsal sepal and petals are fused, forming a hood or "galea" over the column and the dorsal sepal tapers to a point. The petals are wider than those of similar greenhoods and extend beyond the end of the dorsal sepal. The lateral sepals are held closely against the galea, NaNsigfig=1NaNsigfig=1 long and have thickened, club-like tips. The labellum is small and not visible from outside the flower. Flowering occurs from May to July.[1] [2]
Pterostylis platypetala was first formally described in 2015 by David Jones and Christopher French from a specimen collected in the Wandoo National Park and the description was published in Australian Orchid Review.[3] The specific epithet (platypetala) is derived from the Ancient Greek words πλατύς (platús) meaning “flat”[4] and petalon meaning "petal", referring to the broad edges of the petals.
The broad-petalled snail orchid grows in salmon gum and wandoo woodland and under melaleucas on the edge of winter-wet areas. It occurs between Kalbarri and Brookton.
Pterostylis platypetala is listed as "not threatened" by the Government of Western Australia Department of Parks and Wildlife.