Epiphytic herbs. Roots terete, not branching, glabrous, smooth. Stem patent-ascending to erect, leafy, rooting at the base, not branching or sparsely branching in the basal part. Leaves conduplicate, articulate, distichous, oblong to linear, often semi-terete, apex obtuse to acute, mucronate; leaf sheaths finely transversely wrinkled. Inflorescences lateral, solitary or fascicled, racemose, 1–5-flowered. Flowers inconspicuous, resupinate or not, c. 0.3–1.0 cm wide, opening a few at a time, distichous, green or greenish yellow, becoming more yellow with age, sometimes scented like vanilla. Sepals entire, free, ovate-oblong, often sharply keeled externally. Petals narrower than sepals. Labellum not spurred, concave, entire or trilobed, rigidly attached to column, with an oblong, papillose callus basally; labellum apex usually apiculate. Column without a foot; anther cucullate, rostrate; pollinia four, subspherical; stipe about as long as pollinia. Capsule oblong, subsessile.