Glabrous, fibrous-rooted perennial. Stems twining, sometimes muricate. Petiole 2.5-3.8 cm long. Lamina 5.5-16 × 4-14 cm, broad-ovate, entire or with 2 small outwardly directed lobes towards the base, deeply cordate with ± rounded sinus; apex usually acuminate. Infl. axillary, cymose, 1-few-flowered; peduncles stout; pedicels to 1 cm long, stout. Bracts small, caducous. Sepals 1.7-2 cm long, elliptic, unequal; outer 2 or 3 sepals with long patent or curved awns, the inner at most mucronate. Corolla 9.5-11 cm diam. across the patent limb, white with green mid-petaline bands outside, salverform; tube narrow-cylindric, 8.25-9.5 cm long. Stamens with exserted part 1.5-2.5 cm long; filaments glabrous. Capsule 2.5-3 cm long, ovoid, prominently beaked. Seeds c. 10 × 7 mm, deep brown, glabrous.