Tên Khoa học: Begonia langsonensis C.-I Peng & C. W. LinTên tiếng Anh: Tên tiếng Việt: Thu hải đường lạng sơnTên khác:
Herb, monoecious, rhizomatous. Rhizome creeping, to 10 cm or longer, 0.6–1.7 cm thick, internodes congested, glabrous. Stipules deciduous, reddish pale green, widely ovate-triangular, 0.7–1 cm long, 0.7–1.1 cm wide, herbaceous, strongly keeled, glabrous, apex aristate, arista ca. 0.3 cm long. Petioles brownish green, terete, 13–25 cm long, 0.3–0.7 cm thick, glabrous. Leaves alternate, blade asymmetric, obliquely ovate, 11–22.5 cm long, 6–13.5 cm wide, broad side 3.3–6.8 cm wide, basal lobes cordate, 2.7–5.5 cm long, apex attenuate, caudate, base strongly oblique-cordate, margin serrulate and puberulous, thickly chartaceous, adaxially uniformly emerald green, very sparsely minutely scabrescent, abaxially pale green, sparingly puberulous or subglabrous; venation palmate with 6–8 primary veins, midrib distinct, secondary veins 2–4 on each side, minor veins reticulate, all venation prominently raised on upper surface, major and secondary veins prominent on lower surface. Inflorescences axillary, arising directly from rhizome, dichasial cymes branching 4–6 times; peduncle 12–26 cm long, subequal to leaves, glabrous; bracts and bracteoles caducous, white, pale green to pinkish, bracts widely ovate to very widely ovate, 0.6–0.9 cm long, 0.6–0.8 cm wide, flat, margin denticulate to biserrate, puberulous or glandular hairy, bracteoles widely ovate to orbicular, margin denticulate, glandular hairy, gradually smaller toward upper part of the inflorescence. Staminate flower: pedicel ca. 2.2 cm long, tepals 4, outer 2 broadly ovate to orbicular, 10–15 mm long, 11–14 mm wide, abaxially pink, glabrous, adaxially pinkish, inner 2 pinkish, lanceolate, 6–9 mm long, 2.5–3.5 mm wide; androecium zygomorphic, ca. 5 mm across; stamens 25–40; filaments coalescent, not forming a stalk at base; anthers yellow, slightly compressed, obovate, ca. 1.5 mm long, apex retuse, shorter than filaments. Pistillate flower: pedicel 1.8–2.6 cm long, tepals 3, outer 2 pink or pinkish on both surfaces, orbicular, 11–15 mm long, 13–18 mm wide, inner 1 pinkish, oblanceolate, 7–11 mm long, 3–4 mm wide; ovary whitish green to pinkish, trigonous-ellipsoid, 12–15 mm long, ca. 5 mm thick (wings excluded), with sparse sessile glands, 3-winged, wings unequal, pinkish, lateral wings narrower, 6–4.5 mm wide, abaxial wing crescent-shaped, 5–7 mm wide; styles 3, fused at base, yellow, 4–5.5 mm long, stigma spirally twisted. Capsule trigonous-ellipsoid, 13–16 mm long, ca. 5 mm thick (wings excluded), greenish or reddish when fresh; wings unequal, lateral wings 3–5 mm wide, abaxial wing crescent-shaped, 7–9 mm wide. Somatic chromosome number, 2n = 30.
Distribution and ecology
Endemic to Huu Lung Protected Area, Huu Lien District, Lang Son Province, Vietnam (Figure 3). On semishady cliff face or steep limestone slopes in evergreen broad-leaved forest, elevation ca. 125–165 m.
The specific epithet refers to Lang Son Province, where the new species was discovered.
Begonia langsonensis somewhat resembles B. ornithophylla Irmsch. (southwest Guangxi, China) in leaf shape and aspect. However, B. langsonensis is nearly glabrous throughout, whereas B. ornithophylla has sericeous petiole, puberulous abaxial blade, as well as velutinous to villous pedicel and peduncle. In addition, B. langsonensis differs from the latter in the bracts widely to very widely ovate (vs. ovate-triangular) as well as the primary and secondary veins on leaf adaxial surface elevated (vs. sunken).