Pterostylis depauperata

Pterostylis depauperata, commonly known as the keeled greenhood, is a species of orchid endemic to Queensland. Flowering plants have a rosette of leaves at the base of a flowering stem with a single small white flower with pale green marks, and a few small stem leaves. Non-flowering plants only have a rosette of leaves. All three sepals on the flower have relatively long, thread-like tips.

Description
Pterostylis depauperata is a terrestrial, perennial, deciduous, herb with an underground tuber and which often grows in colonies. Non-flowering plants have a rosette of between three and seven egg-shaped, greyish green leaves lying flat on the ground. Each leaf is 10-40 mm long and 5-10 mm wide. Flowering plants have a single flower 15-17 mm long and 8-10 mm wide on a flowering stem 80-200 mm high with a few small stem leaves. The flowers are white with pale green striations. The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The dorsal sepal has a thread-like tip 10-13 mm long and lateral sepals are erect, held closely against the galea and have thread-like tips 17-20 mm long. The labellum is 8-10 mm long, about 3 mm wide, dark brown and curved, and just protrudes above the sinus. Flowering occurs from March to August.

Taxonomy and naming
Pterostylis depauperata was first formally described in 1943 by Frederick Bailey from a specimen collected near Cairns. The description was published in the Botany Bulletin of the Queensland Department of Agriculture.

Distribution and habitat
The keeled greenhood grows with grasses and small shrubs in woodland and forest between Cooktown and Ravenshoe at altitudes above 500 m.