Epiphytic, occasionally lithophytic or terrestrial perennial herbs.Stems usually forming pseudobulbs, clustered or less commonly spaced out on a creeping rhizome, sometimes branched or superposed (emerging from nodes above the base of the previous pseudobulb), 1- to several-noded, with 1 to several leaves.Leaves linear, lanceolate, oblanceolate or elliptic, varying in texture.Inflorescence (comprising peduncle, rhachis and flowers) 1- to many-flowered, simple or branching.Floral bracts erect to reflexed, setiform, lanceolate, ovate or obovate, acute or acuminate to mucronate.Flowers usually non-resupinate, very small or medium-sized, rarely large, usually fragrant, often pubescent, green, yellow, white, pink, mauve or orange, rarely red.Dorsal sepal lanceolate to ovate; lateral sepals ± oblique, joined to the column-foot to form a mentum.Petals linear to obovate.Lip usually 3-lobed but sometimes entire, with or without a basal callus, glabrous, pubescent or farinose, often recurved, sometimes fleshy and difficult to flatten without breaking.Column porrect, usually short and stout with a ± elongate foot; pollinia 2, ovoid; stipe 1, square or sub-triangular to oblong or linear; viscidium small to large, round or ellipsoid; rostellum usually obscure, bifid in front, rarely slightly elongated or beak-like.