18. Cynanchum insulanum (Hance) Hemsley, J. Linn. Soc., Bot. 26: 107. 1889.
海南杯冠藤 hai nan bei guan teng
Herbs, glabrous except for pubescent nodes, petioles, and leaf margin. Rhizome nodes sometimes forming globose tubers. Stems twining, to 60 cm. Leaves opposite; petiole 1-15 mm; leaf blade oblong-hastate, ovate-triangular, to linear-lanceolate, 1-4 × 0.1-1.5 cm, base rounded to subcordate-hastate, apex acute or short apiculate; lateral veins 5 or 6 pairs. Inflorescences umbel-like, much shorter than leaves, 4- or 5-flowered. Sepals oblong, ca. 1 × 0.5 mm, acute; basal glands 5. Corolla greenish white, subrotate; tube ca. 0.5 mm; lobes ovate-oblong, ca. 2 × 1 mm, acute. Corona tube cupular, thin membranous, ca. 2 mm, longer than gynostegium, longitudinally plicate; anthers nearly square, appendages ovate; pollinia oblong. Stigma head capitate, included within anthers. Follicles lanceolate, 4.5-5 cm × 7-8 mm, with 2 inconspicuous longitudinal ridges, glabrous. Seeds oblong, ca. 3 mm; coma ca. 2 cm.
* Two varieties: 0-100 m. Guangdong, Guangxi, Hainan