Dendrobium biconvexum, commonly known as the Mount Windsor rock orchid,[1] is a species of lithophytic orchid that is endemic to tropical North Queensland, Australia. It has spindle-shaped pseudobulbs, between two and four thick, leathery leaves and up to seventy five white or cream-coloured flowers with purple markings on the labellum.
Dendrobium biconvexum is a lithophytic herb with spreading roots and green pseudobulbs NaNsigfig=1NaNsigfig=1 long, NaNsigfig=1NaNsigfig=1 wide and tapering towards both ends. Each pseudobulb has between two and four thick, leathery dark green leaves originating from its top, the leaves NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. Between forty and seventy five white to cream-coloured flowers NaNsigfig=2NaNsigfig=2 long and NaNsigfig=2NaNsigfig=2 wide are arranged on a flowering stem NaNsigfig=1NaNsigfig=1 long. The dorsal sepal is oblong, NaNsigfig=2NaNsigfig=2 long and NaNsigfig=2NaNsigfig=2 wide. The lateral sepals are NaNsigfig=2NaNsigfig=2 long, NaNsigfig=2NaNsigfig=2 wide, curved and spread widely apart from each other. The petals are linear to oblong, NaNsigfig=2NaNsigfig=2 long and about 2sigfig=1NaNsigfig=1 wide. The labellum is cream-coloured with purple markings, NaNsigfig=1NaNsigfig=1 long and NaNsigfig=2NaNsigfig=2 wide with three lobes. The sides lobes are erect and curved and the middle has a short point on the end. Flowering occurs between July and September.[2]
The Mount Windsor rock orchid was first formally described in 2006 by David Jones and Mark Clements from a plant grown in the Australian National Botanic Gardens from a specimen collected on the Mount Windsor Tableland west of the Daintree National Park. It was given the name Thelychiton biconvexus and the description was published in Australian Orchid Research.[3] In 2014, Julian Shaw changed the name to Dendrobium biconvexum.[4] The specific epithet (biconvexum) is derived from the Latin words bis meaning "twice"[5] and convexus meaning "arched outward" or "protuberant",[5] referring to the shape of the pseudobulbs.
Dendrobium biconvexum grows on rocks, cliffs and boulders in or near to rainforest in North Queensland, Australia. It has been recorded on a few mountainous area in and around the Ngalba Bulal National Park.