Description from Flora of China
Convolvulus nil Linnaeus, Sp. Pl. ed. 2. 1: 219. 1762; C. hederaceus Linnaeus; Ipomoea hederacea (Linnaeus) Jacquin; I. nil var. setosa (Blume) Boerlage; I. scabra Forsskål; I. setosa Blume; I. trichocalyx Steudel; I. vaniotiana H. Léveillé; Pharbitis nil (Linnaeus) Choisy.
Herbs annual, twining, with retrorsely hirsute axial parts. Stems 2-5 m. Petiole 2-15 cm; leaf blade broadly ovate or nearly circular, 4-15 X 4.5-14 cm, hirtellous, base cordate, margin entire or ± 3- (or 5)-lobed, apex acuminate. Inflorescences axillary, 1- to few flowered; peduncle 1.5-18.5 cm; bracts linear or filiform, 5-8 mm, spreading hirtellous. Pedicel 2-7 mm. Sepals lanceolate, ± equal, 1-2.5 cm, abaxially spreading hirsute, subglabrous apically, with a linear acumen, hairs swollen based. Corolla pale to bright blue with whitish tube, fading to pinkish in age, funnelform, 5-6(-8) cm, glabrous. Stamens included, unequal. Pistil included; ovary glabrous, 3-loculed. Stigma 3-lobed. Capsule straw colored, ovoid to ± globose, 8-10 mm in diam., glabrous. Seeds black, ovoid-trigonous, 5-6 mm, gray puberulent. 2n = 30*.
The seeds have a number of local medicinal uses.
Thickets on mountain slopes, waysides, fields, hedges; 0-1600 m. Cultivated or escaped. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Nei Mongol, Ningxia, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [?Japan (Ryukyu Islands), Kashmir, Myanmar, Nepal, New Guinea, Pakistan, Sri Lanka, Thailand; native of South America, now nearly circumtropical]