Description from Flora of China
Herbs, deciduous. Tubers subglobose, to 2.2 cm in diam.; stolons threadlike, to 35 cm, glabrous. Stems often reddish, to 50 cm tall. Leaves basal and cauline; stipules caducous, ovate, 5-7 mm, margin serrulate; petiole often reddish, to 25 cm; blade ovate, asymmetric, to 27 × 18 cm, abaxially glabrous, adaxially sparsely scabrous, venation palmate, 6- or 7-veined, base oblique, cordate, margin irregularly serrulate, shallowly lobed, apex acute or shortly acuminate. Inflorescences glabrous; bracts caducous, narrowly ovate or elliptic, 5-12 × 4-7 mm, thinly papery, glabrous, margin serrate, apex acute. Staminate flowers: pedicel 0.7-2.5 cm; tepals 2, pinkish to pale purple, cordate or oblate, 0.9-2.2 × 1.4-2.1 cm, glabrous; stamens 20-49; filaments 1.6-3 mm; anthers obovoid, 1.2-1.8 mm. Pistillate flowers: pedicel 1-3.5 cm; tepals 2, rarely 3, pinkish to pale purple, suborbicular, 1.2-1.5 cm, base oblique, slightly cordate; ovary obovoid, glabrous, 3-loculed; placentae axile, bilamellate; styles 3, fused at base, 1.5-4.2 mm; stigmas 2-cleft, spiraled. Capsule pendulous, obovoid-globose, glabrous, subequally 3-winged. Fl. Oct, fr. Nov. 2n = 36*.
This species is similar to Begonia grandis but differs by the presence of stolons and the 2-tepaled staminate and pistillate flowers.
● On moist, semishaded rocky slopes; 300-1000 m. W Taiwan.