Description from Flora of China
Calonyction mollissimum Zollinger, Syst. Verz. 2: 128, 131. 1854; C. mollissimum var. glabrior Miquel; Ipomoea mollissima (Zollinger) H. Hallier; I. mollissima var. glabrior (Miquel) Boerlage; I. yomae Kurz.
Plants perennial, woody, twining, occasionally prostrate, pubescent, glabrescent. Stems terete or angular, smooth or with small hooks. Petiole slender, 3-10 cm; leaf blade ovate to circular, 5-14 X 3-10 cm, pubescent or subglabrous, base cordate, margin entire, undulate, or acutely angled, apex long acuminate, mucronulate. Inflorescences 1- to few flowered; peduncle 4-15 mm. Pedicel 0.7-1.5 cm, sometimes angular, thicker distally, clavate in fruit, to 2 cm, recurved. Flowers nocturnal. Sepals slightly unequal, outer 2 longer, 1.2-1.8 cm, enlarged in fruit, broadly elliptic to circular, thinly leathery, apex rounded to emarginate, mucronulate. Corolla white, greenish outside, salverform, 12-17 cm; limb 8-10 cm in diam. Stamens minutely exserted; filaments inserted near mouth of tube, ca. 2 mm, base pubescent. Pistil slightly exserted; ovary glabrous. Stigma 2-lobed. Capsule at first enclosed by sepals that later reflex, ovoid, ca. 1.5 cm, apiculate, 4-valved. Seeds 6-8 mm, densely gray-brown woolly. Fl. Sep-Oct, fr. Sep-Oct.
Thickets, forests, roadsides; 0-1200 m. Hainan [Indonesia, Myanmar, Philippines, Thailand].