Schltr., Repert. Spec. Nov. Regni Veg. Beih. 4: 285 (1919)
Epiphytic herbs. Stems erect or pendent, completely enclosed by distichously arranged, persistent leaf-sheaths, rooting mostly from base or lower part. Leaves distichous, duplicate, terete, semi-terete, broadly semi-terete, or triquetrous, adaxial surface channelled, articulate, dilated and sheathing at base, deciduous. Inflorescence axillary, racemose, few- to many-flowered; floral bracts shorter than pedicellate ovary. Flowers resupinate, usually widely opening, often white or yellowish. Sepals free, subsimilar, dorsally usually carinate, lateral sepals often slightly larger, oblique. Petals similar to dorsal sepal. Labellum sessile, firmly attached to column base, saccate or spurred, trilobed, lateral lobes erect beside entrance to spur, midlobe larger, often narrowed and with appendages at base; spur cylindrical, attenuate toward tip, usually arcuate, interior unornamented. Column prominently winged, foot absent, clinandrium deeply cleft in front; pollinia two, solid, waxy, globular, provided with a narrow, elongate pore, attached by a common linear to subelliptic, tapering stipe to a broad viscidium; rostellum acute, bifid.