Epiphytic or lithophytic herbs. Stems branched, often to several metres long, leafy, scrambling. Leaves distichous, oblong or gradually narrowing toward apex, apex bilobed, coriaceous, base sheathing. Inflorescence lateral, often branched, ascending or pendent, few- to many-flowered. Flowers resupinate, often showy, usually widely opening, often spider-like, often fragrant. Sepals and petals similar, free, ovate or (narrowly) oblong to linear, usually widened toward apex, spreading. Lateral sepals and petals often falcate-curved. Labellum trilobed, motile, attached to the column foot by a strap of tissue, base saccate or spurred, midlobe with a raised, central ridge or callus. Column with an inconspicuous or absent foot; pollinia four, appearing as two masses, those in each pair unequal, waxy, stipe broad, viscidium broadly ovate or saddle-shaped. Capsule cylindrical.