Description from Flora of China
Convolvulus littoralis Linnaeus, Syst. Nat. (ed. 10) 924. 1759; C. denticulatus Desrousseaux; Ipomoea denticulata (Desrousseaux) Choisy, non R. Brown.
Herbs perennial. Stems prostrate, rooting at nodes, or twining, slender, mostly glabrous. Petiole 0.5-7 cm; leaf blade ovate to oblong, occasionally circular or reniform, 1-10 X 1-7.5 cm, glabrous or nearly so, base cordate, margin entire or minutely undulate to angular, or ± 3-lobed, apex acute, obtuse or emarginate, mucronulate. Inflorescences usually 1- (less often few) flowered; peduncle 0.1-3 cm; bracts early deciduous, 1-2 mm. Pedicel 1-4 cm, glabrous. Sepals unequal, glabrous; outer 2 concave, oblong-elliptic, 6-10 mm, apex acute to obtuse; inner 3 elliptic to nearly circular, 0.8-1.2 cm. Corolla pink or pink-purple, with a darker center, funnelform, 3-4.5 cm, glabrous. Stamens included; filaments unequal, glandular pubescent on basal 1/2. Pistil included; ovary glabrous. Stigma 2-lobed. Capsule depressed-globose, ca. 9 mm in diam. Seeds black, ovoid, 3.5-4 mm, glabrous. 2n = 30, 60.
Long confused with Ipomoea gracilis R. Brown, a distinct species that is endemic to Australia; the nomenclature, distribution, and ethnobotanical significance of I. littoralis have been discussed by Austin (Econ. Bot. 45: 251-256. 1991).
According to Xing et al. (Guihaia 14: 151-156. 1994) and Huang et al. (Taiwania 39: 1-26. 1994), Ipomoea gracilis R. Brown occurs on the South China Sea Islands (Nanhai Zhudao);
however, material was not available for study. It is likely that the plants collected belong to I. littoralis, and not I. gracilis.
Sandy seashores, coastal thickets, forest floors; 0-100 m. Hainan (Nanhai Zhudao), Taiwan [Cambodia, India, Indonesia, Japan (Ryukyu Islands), Malaysia, Myanmar, New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; Africa, N Australia, Pacific Islands]