Epiphytic or occasionally lithophytic, rarely terrestrial herbs. Roots many, often tangled. Stem pendent or erect. Leaves oblong, narrowly ovate, elliptic or narrowly ovate, obtuse, acute or acuminate, sometimes unequally emarginate, persistent. Inflorescence racemose, usually few-flowered; peduncle and rachis wiry; floral bracts minute. Flowers resupinate, lasting longer than two days, strongly fragrant. Sepals and petals free, similar in length, spreading. Labellum rigidly joined to apex of column foot, either in line with foot or at a right angle to it, saccate, spurred, trilobed; disc not readily differentiated from spur and midlobe, side lobes not in contact with column or column foot, variously shaped, midlobe not readily differentiated from front wall of spur, appearing to be an extension of it, variously shaped; spur either subcylindical and curved slightly forward or hemispherical, a digitiform or claviform callus covered with trichomes arising from its distal side close to orifice and directed toward its apex. Column without wings, column foot less than half the length of column proper, not readily differentiated from it; anther cap shallow, pollinia four, in two unequal, closely appressed pairs, stipe longer than wide, viscidium set at an acute angle to stipe; rostellum beaked, porrect or slightly upcurved, apex bifid.