Leafless saprophytes with underground rhizomes. Stems climbing, slender, flexuous, much branched, with 1 root and 1 scale at each node, glabrous. Inflorescences racemese or panicles, terminal and lateral in axils of upper scales, glabrous. Flowers not opening widely, glabrous throughout; sepals and petals connivent, free; lip sessile at base of column, loosely embracing column at base, with numerous transverse parallel ridges on each side of thick median longitudinal ridge; column slightly curved, tapering basally, joined with thick median ridge of lip; anther terminal, erect, conical, 2-celled at base; pollinia 2, cleft, soft granular; stigma in semiorbicular cavity under short rostellum. Fruit slender. Seeds with thick coat, surrounded by broad wing.
Three species, from India, Indochina and tropical Asia to Australia. One species in Taiwan.