Pterostylis aquilonia, commonly known as the northern cobra greenhood, is a species of orchid endemic to Queensland. As with similar orchids, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves, but the flowering plants lack a rosette and have a single flower with leaves on the flowering spike. This greenhood has a relatively large green, white and reddish-brown self-pollinating flower.
Pterostylis aquilonia is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette of light green leaves NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. Flowering plants have a single flower NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide borne on a spike NaNsigfig=1NaNsigfig=1 high. The flowers are white, green, and reddish-brown. The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The dorsal sepal curves forward and ends with a short point. The lateral sepals are erect with thread-like ends NaNsigfig=1NaNsigfig=1 long with their tips bent forwards. The lateral sepals are held closely against the galea, and there is a broad, flat, platform-like sinus between their bases. The labellum is NaNsigfig=1NaNsigfig=1 long, about 2sigfig=1NaNsigfig=1 wide and brown while slightly protruding above the sinus. Flowering occurs from May to June.[1]
Pterostylis aquilonia was first formally described in 1997 by David Jones and Bruce Gray. The description was published in The Orchadian from a specimen collected near Herberton.[2] The specific epithet (aquilonia) is a Latin word meaning "north" or "northern".[3]
The northern cobra greenhood grows in forest on the higher parts of the Atherton Tableland.