Rhizomes extensive and far-creeping. Stems glabrous, vigorously twining, often tinged purple where exposed to sunlight. Petioles 3-11 cm long, usually glabrous, sometimes hairy. Lamina 5-18 × 3.5-15 cm, triangular-ovate, sagittate-ovate or hastate, usually glabrous; base deeply cordate with rounded sinus and 1-2 small lobes on each side; apex acute to acuminate. Fls solitary; peduncles 8-20-(30) cm long, usually narrowly winged. Bracts at anthesis imbricate, 2-3.4 × 1.8-3.6 cm, broad-ovate, slightly > calyx; base cordate; apex acute to mucronate. Sepals 1.5-1.8 cm long, ± ovate-lanceolate. Corolla 5.2-8 cm long and 5.5-8 cm diam. across limb, usually white, very rarely pale pink; lobes very shallow and inconspicuous; mid-petaline area of tube shining outside. Stamens c. 3 cm long; filaments with glandular hairs in lower 1/2. Ovary 1-locular. Style glabrous, = or slightly > stamens. Capsule 1-1.5 cm long, subglobose. Seeds 4-5 mm diam., ± triangular-ovoid with rounded outer surface and slightly concave inner faces, smooth, black.