King & Pantl., J. Asiat. Soc. Bengal, Pt. 2, Nat. Hist. 66: 591 (1897)
Epiphytic herbs. Stems enclosed in leaf-sheaths. Leaves fleshy, linear, unequally bilobed, lobules acute, jointed and sheathing at base. Inflorescence racemose, lateral, several-flowered. Flowers resupinate, usually opening successively, short-lived. Sepals and petals free, subequal, lateral sepals attached to column base, usually broader. Petals shorter than sepals. Labellum sessile, narrowly but firmly adnate to column foot at a right angle, sides enveloping or parallel with the column, base with a slit-like opening leading to a hidden pouch, trilobed, lateral lobes parallel to or embracing the column, midlobe linear to narrowly ovate; spur absent or short-saccate (B. calcarata Aver.). Column with an abbreviated foot; pollinia two, waxy, ovoid, slightly grooved or with a small cavity, attached by a linear-oblong stipe to a viscidium.