Calochilus imperiosus, commonly known as the imperial beard orchid, is a species of orchid endemic to northern Australia. It has a single leaf and up to fifteen dull green flowers with red or purple markings and a labellum with a pinkish red "beard".
Calochilus imperiosus is a terrestrial, perennial, deciduous, herb with an underground tuber and a single leaf which is half developed at flowering time, NaNsigfig=1NaNsigfig=1 long, NaNsigfig=1NaNsigfig=1 wide when fully developed. Between five and fifteen dull green flowers with red or purple markings, NaNsigfig=2NaNsigfig=2 long and NaNsigfig=1NaNsigfig=1 wide are borne on a flowering stem NaNsigfig=1NaNsigfig=1 tall. The dorsal sepal is NaNsigfig=1NaNsigfig=1 long and about 8sigfig=1NaNsigfig=1 wide. The lateral sepals are a similar length but about 5sigfig=1NaNsigfig=1 wide. The petals are NaNsigfig=2NaNsigfig=2 long and about 4sigfig=1NaNsigfig=1 wide. The labellum curves downwards and is NaNsigfig=1NaNsigfig=1 long and about 9sigfig=1NaNsigfig=1 wide. The base of the labellum has glossy purple calli and two purple ridges. The middle section has pinkish red hairs up to 5sigfig=1NaNsigfig=1 long and there is a narrow tip about 3sigfig=1NaNsigfig=1 long. Flowering occurs from December to February but each flower only lasts two to four days.[1]
Calochilus imperiosus was first formally described in 2004 by David Jones and the description was published in The Orchadian from specimens collected south of Cooktown.[2] The specific epithet (imperiosus) is a Latin word meaning "possessed of command", "mighty" or "domineering".[3]
The imperial beard orchid grows in grassland and grassy woodland or forest between Cooktown and Herberton in north Queensland and near Kapalga in Kakadu National Park.