Terrestrial or less commonly lithophytic herbs, chlorophyll deficient (heteromycotrophic) or holomycotrophic. Roots basal, often with a well-defined white velamen. Perennating organ stem-like or pseudobulbous if above ground, rhizomatous or tuberous if subterranean, cylindrical, fusiform, conical or ovoid, homoblastic. Leaves linear, lanceolate, ovate or elliptic, acute to acuminate, coriaceous, articulate or not to a sheathing base; rarely lacking chlorophyll and scale-like in holomycotrophic species. Inflorescence lateral, simple or rarely branching; bracts persistent. Flowers green or brown to coloured, occasionally bicoloured. Dorsal sepal free, oblong, elliptic, lanceolate or oblanceolate, reflexed, erect or porrect; lateral sepals oblique at base and decurrent on column foot, otherwise similar to dorsal sepal. Petals free, similar or dissimilar to sepals, often larger, broader and distinctively coloured compared to sepals. Labellum free to base or fused to base of column, trilobed, spurred at base, lateral lobes free or fused to base of column, midlobe flat or convex; callus two- or three-ridged or papillose. Column usually with a foot; pollinia two, globose, stipe solitary, triangular to oblong, viscidium oblong, elliptic to lunate. Ovary cylindrical, grooved. (PC).