Ipomoea caloxantha Diels, Notes Roy. Bot. Gard. Edinburgh 5: 203. 1912.

Herbs perennial, prostrate (and ?twining), 1-3 m, almost completely glabrous. Petiole 1.3-2.2 cm, pilose apically; leaf blade deeply 3-lobed, 3-3.5 X 2-2.5 cm, base cordate; basal lobes entire or undulate-lobate, median lobe longest, lanceolate, long attenuate. Inflorescences 3-5-flowered; peduncle 2.5-4.5 cm; bracts 2, minute scales. Pedicel 6-13 mm. Sepals obovate, concave, subequal, 6-7 mm, glabrous, margin thinner, sometimes recurved above middle, apex rounded to emarginate, mucronulate. Corolla bright yellow, broadly funnelform, 3-4 cm, midpetaline bands hairy at apex only. Stamens unequal; anthers straight. Pistil equal to longest stamens, included; ovary broadly ovoid, 2-locular, glabrous; ovules 4. Stigma 2-globose. Fruit unknown. Fl. Sep.

Known only from the type collection, made by George Forrest in 1905 in the valley of the Mekong at "the crossing of the Teng-yueh and Dalifu road." On first sight, the deeply trilobate leaves of Merremia caloxantha suggest M. gemella and M. hederacea of sect. Merremia. However, the anthers that remain straight at dehiscence, the much larger corollas, and the corolla pubescence confined to the apex of the weakly delineated midpetaline bands indicate that this species may belong to sect. Xanthips. Further collections are needed to elucidate its relationships.

* Dry exposed rocky slopes; ca. 1400 m. Yunnan (Yongping Xian)