二色山牵牛 er se shan qian niu

Vines to 12 m, woody. Stems 4-angled, sulcate, pubescent, soon glabrescent, pilose at nodes. Petiole 3-4 cm; leaf blade broadly ovate to ovate-lanceolate, ca. 10 × 5 cm, both surfaces glabrous, palmately 5-7-veined, base cordate, margin remotely dentate or sometimes entire, apex acuminate to acute. Racemes axillary or terminal, erect; peduncle pubescent; bracts lanceolate, pubescent, 1-3-veined, margin dentate, apex acute; bracteoles ovate-lanceolate, 1-1.4 × 0.8-1 mm, abaxially tomentose, apex acuminate. Calyx annular, unlobed. Corolla to 2 cm; tube yellowish brown; lobes ovate-elliptic, ca. 1.1 cm, subequal, lower lobes red, upper lobes yellow. Anther thecae glabrous, those of lower pair of stamens long spurred at base, those of upper pair of stamens spurred at base of only one theca per anther. Ovary pubescent. Capsule basal part 1-1.5 cm in diam., beak ca. 1.6 cm. Seeds hemispherical, verrucose. Fl. Aug-Nov, fr. Jan-Apr.

Dense forests; 300-800 m. Hainan [Vietnam].