Corybas undulatus, commonly known as tailed helmet orchid, is a species of terrestrial orchid endemic to eastern Australia. It has a single leaf and a single translucent grey flower with reddish markings, and a labellum with a bristly surface, fine teeth on the edge and a small tail on the tip.
Corybas undulatus is a terrestrial, perennial, deciduous, herb with a single leaf NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. The leaf is greyish green on the upper surface and silvery green or reddish on the lower side. There is a single translucent grey flower with purplish red and white markings, NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide which leans backwards. The dorsal sepal is spatula-shaped to egg-shaped with the narrower end towards the base, NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. The lateral sepals are thread-like, about 3.5sigfig=1NaNsigfig=1 long and 0.5sigfig=1NaNsigfig=1 long and the petals are similar but shorter. The labellum is tube shaped at its base and for about half its length before opening into a broad heart-shaped dish NaNsigfig=1NaNsigfig=1 long and wide. This part of the labellum has a whitish centre and is covered with tiny bristles. The edges of the labellum have tiny teeth and there is a small tail-like tip on the lower edge. Flowering occurs from May to July.[1] [2]
The tailed helmet orchid was first formally described in 1833 by Richard Cunningham, who gave it the name Corysanthes undulata and published the description in the New South Wales Magazine.[3] In 1942 Herman Rupp changed the name to Corybas undulatus.[4] The specific epithet (undulatus) is a Latin word meaning "wavy".[5]
Corybas undulatus is an uncommon, often overlook species growing in grassy and heathy forest in coastal areas of Queensland south from Bundaberg to Jervis Bay in New South Wales.