Pterostylis tanypoda, commonly known as the swan greenhood, is a species of greenhood orchid endemic to New Zealand. Both flowering and non-flowering plants have a rosette of leaves lying flat on the ground and flowering plants have up to seven crowded, inconspicuous bluish-green and white-striped flowers.
Pterostylis tanypoda is a terrestrial, perennial, deciduous, herb with an underground tuber. Non-flowering plants have a stalked rosette of bluish-green, egg-shaped leaves which are NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. Up to seven bluish-green and white-striped flowers are crowded together on a fleshy flowering stem NaNsigfig=1NaNsigfig=1 high with many stem leaves similar to the rosette leaves but smaller. 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. The labellum is short, broad and blunt with a dark green lobe on the upper end. Flowering occurs from October to January.[1] [2]
Pterostylis tanypoda was first formally described in 1997 by David Jones, Brian Molloy and Mark Clements from a specimen collected near Castle Hill. The description was published in The Orchadian.[3] The specific epithet (tanypoda) is derived from the Ancient Greek words tany- meaning "long"[4] and pous meaning "foot".
This greenhood grows in montane and subalpine grassland on the eastern side of South Island between Marlborough and Southland.