Description from Flora of China
Merremia umbellata var. orientalis H. Hallier, Verslag Staat Lands Plantentuin Buitenzorg 132. 1895 (1896).
Herbs twining or prostrate; axial parts puberulent or glabrous, with milky sap. Stems striate, rooting at nodes. Petiole 1-4(-6) cm; leaf blade ovate, ovate-oblong, or oblong-lanceolate, 3.5-13.5 X 1.3-10 cm, softly whitish puberulent, adaxially more densely so, base cordate, rarely hastate, margin entire, apex emarginate, acute to acuminate. Inflorescences umbelliform cymes, few to many flowered; peduncle (0.5-)2-5(-12) cm; bracts early deciduous, lanceolate, minute. Pedicel 1-2(-3) cm. Sepals strongly concave, slightly unequal; outer 2 broadly elliptic or nearly circular, 0.8-1.4 cm, abaxially pubescent, rounded or emarginate; inner ones usually slightly longer, margin scarious. Corolla white or yellow, funnelform, 2.5-5.5 cm, midpetaline bands with a strip of whitish pubescence apically; limb slightly lobed. Stamens included; anthers not twisted. Ovary glabrous or sparsely pubescent apically. Capsule conical-ovoid, 0.7-1.3 cm X 7-8 mm, glabrous or sparsely pubescent apically, apiculate. Seeds ca. 5 mm, densely spreading long pubescent.
Used in Guangxi for treating infections.
Ooststroom (Blumea 3: 341-342. 1939) compared and contrasted the two varieties (later elevated to subspecies) of Merremia umbellata. Subspecies umbellata is distributed
throughout the American tropics (Mexico, Central America, the West Indies, and South America as far south as Paraguay) and in western tropical Africa. It is a more robust plant,
typically with more and larger flowers per inflorescence, corollas always yellow, capsules subglobose, with broader ovate valves, and seeds pubescent to shortly tomentose, the hairs
only slightly longer on the margins.
Merremia umbellata is clearly recognizable in North and South America, Malaysia, tropical Africa, and the Pacific Islands, but the situation is not so clear on mainland Asia. The limits
of M. umbellata adopted here and in Fl. Reipubl. Popularis Sin. are the same, but these encompass a much greater variation in flower size, color, and number per inflorescence, and
density and in distribution of indumentum than do other regional floras that have circumscribed the species more narrowly. Further study of sect. Xanthips in mainland Asia is needed
before a clearer concept of M. umbellata and its relatives in that section can be reached.
Roadsides, forested valleys, thickets; 0-1600 m. Guangdong, Guangxi, Hainan, Taiwan, Yunnan [?Bangladesh, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Nepal, New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; E Africa, N Australia, Pacific Islands]