Epiphytic or lithophytic herbs. Roots smooth. Stem leafy, covered with leaf bases. Leaves few, distichous, coriaceous, linear, ligulate, obovate or oblong-elliptic, often falcate, unequally bilobed at apex, articulated at base to sheath. Inflorescences axillary, erect to pendent, usually from basal part of stem, simple, few- to several-flowered, usually as long as or longer than leaves, rarely much shorter; bracts triangular, sheathing. Flowers usually flat or campanulate; pedicel and rachis as long as or longer than sepals. Sepals and petals similar, free, spreading, white to olive, sometime spotted with red. Labellum smaller than sepals, trilobed, spurred at base, side lobes erect around column, hairy or glabrous; spur tapering to rounded tip, callus lobed, on back wall within spur. Column terete; pollinia four, ovoid, in two unequally sized pairs, stipe narrowly to broadly spatulate, viscidium elliptic to oblong.