Pterostylis subtilis, commonly known as the thin mountain greenhood, is a species of orchid endemic to New South Wales. It has a rosette of leaves and when flowering a single translucent white flower with dark green lines, a narrow, deeply notched sinus between the lateral sepals and a curved, protruding labellum.
Pterostylis subtilis is a terrestrial, perennial, deciduous, herb with an underground tuber and a rosette of fleshy leaves lying flat on the ground. Each leaf is NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. When flowering, there is a single white flower with dark green lines, NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide which is borne on a flowering spike NaNsigfig=1NaNsigfig=1 high. The dorsal sepal and petals are fused to form a hood or "galea" over the column, the dorsal sepal slightly longer than the petals and all sharply pointed. There is a narrow gap at each side of the flower between the petals and lateral sepals. The lateral sepals are erect with a tapering tip NaNsigfig=1NaNsigfig=1 long and there is a deep, narrow sinus between them. The labellum is NaNsigfig=1NaNsigfig=1 long, about 3sigfig=1NaNsigfig=1 wide, blunt and curved, protruding above the sinus. Flowering occurs in December and January.[1]
Pterostylis subtilis was first described in 2006 by David Jones and the description was published in Australian Orchid Research from a specimen collected in the Barrington Tops National Park.[2] The specific epithet (subtilis) is a Latin word meaning "thin", "fine", "slender" or "acute ".[3]
The thin mountain greenhood grows with grasses on sheltered forest slopes in the Barrington Tops National Park.[4]