Description from Flora of China
Herbs, rhizomatous. Rhizomes creeping, to 2 cm in diam. Stems 40-95 cm tall. Leaves basal and cauline; stipules ovate to very broadly ovate, to 2.6 cm, glabrous, margin entire, apex acuminate, caducous; petiole 10-45 cm; blade broadly ovate to orbicular, asymmetric, 9-34 × 7-29 cm, venation palmate-pinnate, abaxially subglabrous to sparsely hairy, adaxially subglabrous, base obliquely cordate, margin serrulate, undivided or very shallowly divided, apex acuminate to caudate. Inflorescences 12-40 cm, subglabrous; peduncle to 31 cm; bracts caducous, ovate to broadly ovate, to 2.5 × 1.9 cm, margin entire, apex acute. Staminate flowers: tepals 4, pink, outer 2 obovate to orbicular, 1.1-2.8 × 1-2.6 cm, inner 2 oblanceolate to obovate, 1-2.6 cm × 4-13 mm; stamens 78-142; filaments free, 0.8-2.4 mm; anthers obovoid, 2-2.3 mm. Pistillate flowers: ovary ellipsoid, glabrous, 2-loculed; placentae axile, bilamellate; tepals 5, unequal, oblanceolate to orbicular, largest 0.9-2.6 × 0.8-2.3 cm, smallest 0.8-2.4 cm × 4-11 mm; styles 2, fused at base; stigmas 2-cleft, spiraled. Capsule nodding, unequally 3-winged; abaxial wing broadly elliptic to orbicular, 1.9-3.2 × 1.1-2.2 cm; lateral wings smaller, 4-6 mm. Fl. Jun-Oct. 2n = 38*.
This species is similar to Begonia formosana but differs by the abaxial wing of the capsule, which is broadly elliptic to orbicular, 1.9-3.2 × 1.1-2.2 cm.
● Shaded moist broad-leaved forests; 400-2200 m. C and N Taiwan.