Description from Flora of China
Herbs, terrestrial, small to large. Rhizome present or not. Pseudobulbs usually small, conic, ovoid, or subglobose, rarely inconspicuous or cylindric, with roots at base and a few leaves at apex; roots long, stout, pubescent. Leaves sometimes not well developed or not completely spreading at anthesis; blade rarely narrowly ensiform or lorate, ± plicate, but often convolute when young, base contracted into a petiole-like stalk or subsessile, sheathing, articulate or not. Scape arising from leaf axil or from base of pseudobulb, rarely from apex of leafless pseudobulb, erect, usually densely puberulent; inflorescence a terminal raceme, few to many flowered; floral bracts persistent or caducous. Flowers resupinate, small to medium-sized, often opening widely. Sepals similar, free. Petals often smaller than sepals; lip adnate to base of column wings and forming a tube, or adnate only to base of column, or to column foot and free from column itself, lobed or unlobed, base spurred or not; disk often lamellate or ridged, sometimes with callose appendages at base. Column often short and thick, without or with a short foot at base, winged, rostellum lobed or unlobed; stigma lateral; pollinia waxy, 8, in 2 groups, nearly equal or unequal in size; caudicle conspicuous or inconspicuous, commonly adherent to a sticky viscidium.
About 150 species: tropical and subtropical Asia, Australia, New Guinea, and the SW Pacific islands, as well as tropical Africa and Central and NW South America; 51 species (21 endemic) in China.
(Authors: Chen Xinqi (陈心启 Chen Sing-chi); Phillip J. Cribb, Stephan W. Gale)