Pterostylis tristis, commonly known as the midget greenhood, is a species of greenhood orchid endemic to New Zealand. Both flowering and non-flowering plants have a rosette of fleshy leaves lying flat on the ground and flowering plants have up to eight yellowish-green or brownish flowers with pale stripes.
Pterostylis tristis is a terrestrial, perennial, deciduous, herb with an underground tuber. Non-flowering plants have a stalked rosette of between five and seven brownish or yellowish-green leaves which are NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. Up to eight yellowish-green or brownish striped flowers are borne on a fleshy flowering stem NaNsigfig=1NaNsigfig=1 high with many stem leaves similar to the rosette leaves but smaller. The rosette leaves are usually withered by flowering time. The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The galea is NaNsigfig=1NaNsigfig=1 long and wide with the dorsal sepal slightly longer than the petals. The lateral sepals are downturned and joined together for most of their length, each with a short point on its end. The labellum is short, broad and blunt with a smooth lobe on the upper end. Flowering occurs from September to January.[1] [2]
Pterostylis tristis was first formally described in 1886 by William Colenso from a specimen collected on the south bank of the Waipawa River. The description was published in Transactions and Proceedings of the New Zealand Institute.[3] [4] The specific epithet (tristis) is a Latin word meaning "sad".[5] (Colenso described the type specimen as "very small, rather dingy-looking".)
The midget greenhood usually grows in open tussock grassland. It occurs on the South Island east of the main ranges south from the Canterbury region. There are a few old records from the North Island and Stewart Island.