Epiphytic herbs. Stems short or long, erect or pendulous, rooting near base. Leaves flat or terete, usually very narrow, often unequally 2-lobed at apex, articulated with sheath. Inflorescence simple or branched, erect or pendulous; bracts much shorter than pedicel and ovary. Flowers racemose or paniculate; sepals and petals free, similar; lip not mobile, saccate, 3-lobed at mouth of sac, lateral lobes erect, triangular, midlobe triangular to semiorbicular or sagittate, sac conic-cylindrical, with large appendage inside or variously thickened on inner wall and blocking entrance, usually longitudinally septate; column very short; anther terminal, incumbent, operculate, with reduced partitions; pollinia 4, waxy, in 2 groups, stipe narrow or broad, viscidium large or small, sometimes horseshoe-shaped; stigma entire.
About 90 species, from the Himalaya and Sri Lanka through southeast Asia and Indonesia to Papua New Guinea. Two species in Taiwan.