Herbs, epiphytic, lithophytic, or rarely terrestrial. Stems tufted, erect or pendulous, often ± compressed, slender, with many nodes, simple or branched, pseudobulbs absent, enclosed in persistent basal sheaths of leaves. Leaves many, distichous, flat, often twisted at base so that blades all lie in one plane, with tubular amplexicaul sheaths at base, articulate. Inflorescences terminal, lateral, or both, usually rather short, sometimes shortened and capitate, few to many flowered; floral bracts persistent. Flowers resupinate, white or greenish, very small. Sepals free; lateral sepals adnate at base to column foot forming a mentum. Petals often slightly smaller than dorsal sepal; lip adnate at base to column foot, unlobed or sometimes slightly 3-lobed, base saccate, apex recurved, adaxially with a round or concave basal appendage, sometimes lengthened into small keels, sometimes with a medium keel or callus on distal surface or mid-lobe. Column stout, with long and broad foot; anther subterminal, erect; pollinia 6, waxy, subclavate, in 2 groups, on a slender solitary forked caudicle or 2 separate ones, attached to a common viscidium; rostellum erect, large, often 2-lobed.

About 60 species: tropical Asia to Oceania, mainly in Indonesia and New Guinea; four species in China.

(Authors: Chen Xinqi (陈心启 Chen Sing-chi); Jeffrey J. Wood)