Pterostylis macrosepala is a plant in the orchid family Orchidaceae and is endemic to the central-west slopes of New South Wales. As with similar greenhoods, plants in flower differ from those that are not flowering. Non-flowering plants have a rosette of leaves flat on the ground, but those that are flowering have up to eight translucent green flowers with narrow, dark green stripes and up to ten stem leaves.
Pterostylis macrosepala, is a terrestrial, perennial, deciduous, herb with an underground tuber. Non-flowering plants have a rosette of between three and five, egg-shaped to lance-shaped leaves, each leaf NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide with a petiole up to 8sigfig=1NaNsigfig=1 long. Plants that are flowering lack a rosette but have up to eight flowers on a flowering spike NaNsigfig=1NaNsigfig=1 high with between five and ten linear to lance-shaped stem leaves that are NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. The flowers are NaNsigfig=1NaNsigfig=1 long, NaNsigfig=1NaNsigfig=1 wide and the dorsal sepal and petals are joined to form a hood called the "galea" over the column. The galea is translucent green with dark green stripes. The lateral sepals turn downwards and are NaNsigfig=1NaNsigfig=1 long, NaNsigfig=1NaNsigfig=1 wide and joined for more than half their length. The labellum is NaNsigfig=2NaNsigfig=2 long, about 3sigfig=1NaNsigfig=1 wide and pale green with a blackish stripe along its mid-line. Flowering occurs from July to September.[1]
Pterostylis macrosepala was first formally described in 2006 by David Jones and given the name Bunochilus macrosepalus. The description was published in Australian Orchid Research from a specimen collected in the Conimbla National Park.[2] In 2010, Gary Backhouse changed the name to Pterostylis macrosepala.[3] The specific epithet (macrosepala) is derived from the Ancient Greek word makros meaning "long"[4] and the Neo-Latin word sepalum meaning "sepal", referring to the large fused sepals.
This greenhood is only known from the Conimbla Range where it grows in open forest.