Herbs, epiphytic or rarely lithophytic, monopodial, small to medium-sized. Stems erect or pendulous, rarely creeping, long or short, rigid, branched or unbranched, many noded. Leaves few to many, distichous, dorsiventrally flattened or terete, base usually jointed and sheathing, apex bilobed or acute. Inflorescence racemose or paniculate, lateral, axillary or opposite leaves, erect, horizontal, or pendulous, few to many flowered; floral bracts small, much shorter than pedicel and ovary. Flowers small, ± fleshy. Sepals free, usually spreading. Petals free, often smaller than sepals; lip adnate to column by its base or back margins of lateral lobes, immovable, spurred at base, 3-lobed; disk often with longitudinal lamellae or ridges; spur conic, cylindric, or saccate, often longitudinally septate inside, rarely septum reduced to a narrow keel, usually with a callus on back wall and often with outgrowths on front wall closing entrance. Column short, stout, foot short; rostellum small; pollinia 4, appearing as 2 unequal masses, waxy, subglobose, with a common stipe and a solitary small and subglobose to broad and horseshoe-shaped viscidium.

About 100 species: Sri Lanka, India, mainland SE Asia, Malaysia, and Indonesia to the Philippines, New Guinea, Pacific islands, and Australia; 16 species (four endemic) in China.