Description from Flora of China
Melodorum subglabrum Bân; M. vietnamense Bân; M. vietnamense var. calcareum Bân; Uvaria tonkinensis var. subglabra Finet & Gagnepain.
Shrubs to 6 m tall, climbing. Branchlets sparsely stellate pubescent, glabrescent. Petiole 5-10 mm; leaf blade obovate, obovate-lanceolate, oblong, or elliptic, 12-21 × 4-7 cm, papery, abaxially sparsely stellate hairy but soon glabrescent, adaxially glabrous, secondary veins 8-12 on each side of midvein, base rounded to slightly cordate, apex long to shortly acuminate or rarely acute. Inflorescences terminal or leaf-opposed, 1-flowered. Pedicel 1.5-4.5 cm, sparsely stellate hairy. Sepals broadly obovate, 3-4 mm, outside densely stellate, inside concave and glabrous. Petals purple, 1.5-1.9 × 1.5-1.9 cm; outer petals obovate, broadly ovate, or orbicular, outside densely stellate pubescent; inner petals smaller than outer petals. Stamen connectives glabrous or hairy. Carpels cylindric, stellate pubescent or with hairs only at base and apically; ovules 2 per carpel; stigmas apically entire or 2-cleft. Monocarp stipes 2.5-5 cm; monocarps purple, globose, ca. 1 cm in diam.; epicarp smooth. Fl. Feb-Sep, fr. Aug-Dec.
Thickets, open forests; 200-600 m. Guangdong, W Guangxi, Hainan, S Yunnan [Vietnam].