B. serratifolia C. DC. Monoecious, erect or scandent, perennial herb, to 1(2) m long; stems woody at base, glabrous. Stipules oblong-ovate, acuminate, ca 8 mm long; petioles 2-20 mm long; blades strongly asymmetrical, lanceolate to elliptic-lanceolate, somewhat acuminate, inequilateral at base, one side cuneate, the other rounded, 5-9 cm long, 1.5-4 cm wide, membranaceous, glabrous, the margins doubly crenate-serrate, ciliate. Cymes dichotomously branched; flowers pinkish-white; bracts often deciduous, ovate, ca 5 mm long; staminate tepals 4, unequal, the outer 2 ovate, 8-15 mm long, the inner 2 elliptic-lanceolate, about half as long as outer; stamens numerous; pistillate tepals 5, subequal, elliptic, to 10 mm long; styles 3, bipartite; stigmas branched and finally spiraled. Capsules elliptic-oblanceolate, 3-winged, the wings very unequal, the largest triangular, ascending, 1.5 cm wide; seeds very numerous, elliptic, 0.3 mm long. Croat 7374.