Epiphytic or lithophytic herbs. Stem elongate, clambering, rooting from nodes, usually slightly compressed-trigonous, manynoded, rigid, enclosed in persistent leaf-sheaths, sometimes branched. Leaves many, usually densely distichous, flat, rarely semi-cylindrical, bilobulate, rarely obtuse, coriaceous, articulated to a sheathing base. Inflorescence lateral, racemose, few-flowered. Flowers resupinate. Sepals and petals free, similar, petals slightly smaller, both with longitudinal purple lines. Labellum rigidly adnate to column, spurred at base, trilobed, side lobes erect, midlobe often shortly caudate, adaxial surface thickened and cushion-like centrally; spur narrowly conical, with a longitudinal septum or ridge on inner surface, and with a tough appendage on back wall near entrance. Column lacking a column foot, apex with two long and incurved stelidia; pollinia four, arranged in two pairs, slightly unequal, solid, waxy, semi-globular, stipe irregular, much broader than long viscidium crescent-shaped; rostellum abbreviated.