Didymoplexis

Didymoplexis, commonly known as crystal orchids or as 双唇兰属 (shuang chun lan shu), is a genus of terrestrial leafless orchids in the family Orchidaceae, about twenty species of which have been described. Orchids in this genus have swollen, fleshy rhizomes and thin, pale, upright fleshy flowering stems with resupinate, bell-shaped white or pale yellowish brown flowers. They are native to Africa, Madagascar, Southeast Asia, Australia and various islands of the Pacific.
Description.
Orchids in the genus "Didymoplexis" are small, leafless, terrestrial, mycotrophic herbs with a swollen, fleshy rhizome. The flowering stem is thin, upright and fleshy with a few scale-like bracts fleshy and one to a few flowers. The flowers are resupinate, white or pale yellowish brown and often last for less than a day. The sepals and petals are joined at the base to form a short, bell-shaped tube with the tips spreading widely. The labellum is relatively broad and has a band of calli along its midline.
Taxonomy and naming.
The genus "Didymoplexis" was first formally described in 1843 by William Griffith and the description was published in the "Calcutta Journal of Natural History". The name "Didymoplexis" is derived from the Ancient Greek "didymos" meaning "double" or "twin" and "plexis" meaning "twine", "twist" or "weave" referring to the interlocking calli on the labellum.
List of species.
The following is a list of species of "Didymoplexis" recognised by the World Checklist of Selected Plant Families as at October 2018:
Distribution and habitat.
Crystal orchids grow in grassy forest, bamboo thickets and rainforest in India, southern China and Indochina to southern Japan and the Philippines, throughout the Malay Archipelago to New Guinea, Christmas Island, tropical Australia, and the southwest Pacific islands. Some also occur in South West Africa and Madagascar.