Description from Flora of China
Herbs terrestrial, leafless, holomycotrophic. Rhizomes horizontal, tuberous, cylindric, sometimes slightly coralloid, slightly fleshy, usually densely noded. Inflorescence erect, terminal, noded below middle, nodes with tubular or scalelike sheaths, glabrous, yellowish brown or dull brown, usually few to many flowered, rarely 1-flowered, sometimes elongating in fruit. Flowers spreading or nodding, campanulate, urceolate, or cylindric, resupinate or not, cream-brown, yellowish brown, or dull brown, occasionally greenish brown, lip often lighter brown and sometimes with orange markings; pedicel usually elongating in fruit. Sepals and petals united and forming a perianth tube, only apical portions free; perianth tube sometimes dilated and saccate at base, sometimes with a deep sinus between lateral sepals, outer surface often verrucose; petals much smaller than sepals; lip enclosed within perianth tube, adnate to apex of column foot, usually small, usually clawed at base, simple or 3-lobed; disk with a pair of globose calli at base. Column elongate, with a short but distinct column foot at base, winged toward apex, sometimes with a pair of toothlike projections at apex; anther borne on a filament, large, subterminal, incumbent; pollinia 2, granular-farinaceous, usually composed of friable massulae, without caudicles; stigma raised, shield-shaped. Capsule erect.
About 20 species: from NE India through the E Himalayas, across S China to Japan and E Siberia, throughout SE Asia to E Australia and the SW Pacific islands, also in tropical Africa, Madagascar, and the Mascarene Islands; 15 species (nine endemic) in China.
(Authors: Chen Xinqi (陈心启 Chen Sing-chi); Stephan W. Gale, Phillip J. Cribb)