15. Ipomoea aquatica Forsskål, Fl. Aegypt.-Arab. 44. 1775.
蕹菜 weng cai
Convolvulus repens Vahl; Ipomoea repens Roth; I. reptans Poiret; I. subdentata Miquel.
Herbs annual, terrestrial and repent or floating; axial parts glabrous. Stems terete, thick, hollow, rooting at nodes. Petiole 3-14 cm, glabrous; leaf blade variable, ovate, ovate-lanceolate, oblong, or lanceolate, 3.5-17 X 0.9-8.5 cm, glabrous or rarely pilose, base cordate, sagittate or hastate, occasionally truncate, margin entire or undulate, apex acute or acuminate. Inflorescences 1-3(-5)-flowered; peduncle 1.5-9 cm, base pubescent; bracts squamiform, 1.5-2 mm. Pedicel 1.5-5 cm. Sepals subequal, glabrous; outer 2 ovate-oblong, 7-8 mm, margin whitish, thin, apex obtuse, mucronulate; inner 3 ovate-elliptic, ca. 8 mm. Corolla white, pink, or lilac, with a darker center, funnelform, 3.5-5 cm, glabrous. Stamens unequal, included. Pistil included; ovary conical, glabrous. Stigma 2-lobed. Capsule ovoid to globose, ca. 1 cm in diam., woody, tardily dehiscent or ?indehiscent. Seeds densely grayish pubescent, sometimes glabrous. 2n = 30*.
Marshy habitats: ditches, ponds, rice paddies, waste areas. C to S China, native and cultivated [Bangladesh, Cambodia, India, Indonesia, Laos, Malaysia, Myanmar, Nepal, New Guinea, Pakistan, Philippines, Sri Lanka, Thailand, Vietnam; Africa, Australia, Pacific Islands, South America]
Commonly cultivated as a pot herb, Ipomoea aquatica is adapted to a warm, moist climate and cannot survive frost. Several races are recognized (without formal taxonomic designation) based on growing conditions (terrestrial vs. aquatic) and plant and flower color (greenish plants with white flowers vs. purplish tinged plants with lilac flowers). The plants have minor medicinal uses and also are used for forage.