Terrestrial or rarely lithophytic herbs. Roots basal. Perennating organ stem-like or pseudobulbous, cylindrical, fusiform, conical or ovoid, heteroblastic, often angular in cross-section. Leaves linear, lanceolate, ovate or elliptic, acute to acuminate, conduplicate and coriaceous or plicate, articulate at base, usually petiolate, green or mottled with light and dark green, rarely flushed with purple. Infl orescence lateral, usually exceeding leaves, simple or branching; bracts inconspicuous, persistent, rarely with an extrafl oral nectary. Flowers white, yellow, green or brown, sometimes purplestriped; labellum white or yellow with purple venation. Dorsal sepal free, erect to porrect, obovate to spatulate; lateral sepals oblique at base, otherwise similar to dorsal sepal. Petals free, similar or dissimilar to sepals, obovate to elliptic-oblong, often broader than sepals, often porrect. Labellum free to base, trilobed, spurred at the base, callose, lateral lobes free to base of column, midlobe fl at or convex; callus two- or three-ridged. Column with a distinct foot; pollinia two, ovoid or pyriform. Ovary cylindrical, grooved. (PC).