Herbs, terrestrial, rarely epiphytic or lithophytic. Roots hairy. Stem cylindric to pseudobulbous, fleshy, often creeping and rooting in basal part. Leaves 2 to several, thinly textured to fleshy, plicate, petiolate, petiole sheathing at base. Inflorescence apical, erect, unbranched; floral bracts persistent, often recurved or reflexed, lanceolate or setose. Flower usually not resupinate, green, brown, yellow, pink, or purple. Dorsal sepal spreading, free; lateral sepals free or fused, spreading. Petals often narrower than sepals, free, spreading; lip erect, flat, usually concave at base, entire to lobed, auriculate at base or lacking auricles, apical margin entire or toothed, lacking a spur, callus absent. Column lacking a foot, with 2 apical arms on either side of clinandrium, rarely with a dorsal wing or protuberance; anther cap movable, dorsal, dorsiventrally flattened, attached by a slender filament, locules opening ventrally; pollinia 4, almost equal in size, in pairs, clavate, waxy, with 1 delicate viscidium or lacking a viscidium; stigma elliptic to transversely elliptic; rostellum often obtuse or rounded at apex.