Description from Flora of China
Cyathella callialata (Buchanan-Hamilton ex Wight) C. Y. Wu & D. Z. Li; Cynoctonum callialatum (Buchanan-Hamilton ex Wight) Decaisne; Vincetoxicum callialatum (Buchanan-Hamilton ex Wight) Kuntze.
Herbs twining, to 3 m. Stems pubescent along 1 side. Leaves opposite; petiole 1-4 cm; leaf blade abaxially glaucous, oblong or ovate-oblong, 4.5-8 × 2-4 cm, slightly fleshy, base cordate, apex acuminate, basal lobes incurved, sometimes overlapping; lateral veins 6-12 pairs. Inflorescences simple, umbel-like, dense, 6-12-flowered; peduncle 1-7 mm. Pedicel 3-6 mm. Sepals lanceolate, 2-2.5 × 1 mm; basal glands ca. 10. Corolla whitish, drying darker than corona, rotate; tube ca. 1 mm; lobes oblong, ca. 4 × 1.5-2 mm. Corona white, cupular, ca. 3.5 mm, or reduced to membranous ring, apex 2-cleft, with a longitudinal ridge below each sinus. Gynostegium distinctly stipitate. Anthers ± rhomboid, ca. 1 mm, appendages oval; pollinia oblong. Stigma head ovoid, slightly exserted. Follicles oblong-lanceolate, 5-8 × 1-1.5 cm, with 2 wings especially prominent at tip. Seeds oval-oblong, ca. 5 × 3 mm; coma ca. 2 cm. Fl. Aug-Oct, fr. Oct-Dec.
Records of Cynanchum alatum Wight & Arnott in China are based on a misidentification of C. callialatum. Cynanchum alatum appears to be restricted to India and Sri Lanka.
Open woodland, thickets along mountain roadsides; 1000-1500 m. W Guangxi, Yunnan [India, Myanmar, Pakistan]