Lettsomia mastersii Prain, J. Asiat. Soc. Bengal 63: 98. 1894.

Shrubs scandent. Stems terete, villous. Petiole 5-16 cm, villous; leaf blade broadly ovate to circular, 7-17 X 5.5-15 cm, abaxially ± whitish villous, adaxially strigose, base cordate, apex acute. Inflorescences cymose; peduncle 3-8 cm; bracts several, ligulate, ± petiolate, 2-2.4 cm X 3-5 mm, apex acuminate, persistent. Sepals unequal, ± spreading villous abaxially; outer 3 ovate-lanceolate, ca. 9 4 mm, apex acuminate; inner 2 obovate-elliptic, ca. 6 X 3.5 mm, apex obtuse. Corolla red-purple, funnelform, 3.5-4 cm, whitish hirsute outside; limb shallowly lobed. Stamens and pistil included; filaments ca. 1.7 cm, dilated and glandular pubescent at base; anthers oblong, ca. 3.5 mm. Disc ringlike, ca. 0.5 mm high. Ovary glabrous. Style ca. 2.4 cm; stigma capitate, 2-lobed. Berry enclosed by enlarged calyx, dark purple, ovoid-globose, ca. 1 cm. Seeds 4 or fewer, dark brown, ovoid-trigonous. Fl. Sep.

Argyreia mastersii was treated as A. roxburghii (Wallich) Arnott ex Choisy var. ampla (Choisy) C. B. Clarke in Fl. Reipubl. Popularis Sin. and other Chinese floras. A comparison of the type of A. ampla Choisy (Wallich Cat. no. 1420, microfiche seen) revealed that it is quite different from the Chinese plant, which agrees very well with Prain's description and with specimens labelled A. mastersii from Myanmar. Further study of these taxa and A. hookeri C. B. Clarke (Sikkim) is needed.

Open forests or thickets; 800-1300(-1800) m. S and SW Yunnan [NE India, N Myanmar, ?Thailand]