Climbing epiphytic herbs. Stem pendent or climbing, internodes elongate. Leaves many, distichously arranged, coriaceous, linear, lorate to elliptic, apex usually unequally bilobed, articulated to a sheathing base. Inflorescence axillary, either fasciculate with one to several flowers in a cluster or a many-flowered raceme or panicle. Flowers opening widely, lasting about a week, resupinate, usually yellowish with light brown or purple markings. Sepals and petals free, petals slightly smaller than sepals. Labellum firmly fused to column, spurred or saccate at base, trilobed, side lobes erect, midlobe sometimes trilobed, often hairy or papillate; sac or spur often thickened, with a hairy ligulate appendage on back wall just below base of column, completely covering the entrance to the nectariferous cavity. Column cylindric, sometimes broadened at base so as to appear to have a foot-like extension, often with hairy stelidia, foot absent; pollinia four, arranged in two pairs, unequal, solid, waxy, attached by a common linear-oblong stipe to an ovate or elliptic viscidium.