Scientific name: Begonia montaniformis C.-I Peng, C. W. Lin & H. Q.English name: Vietnamese name: Thu hải đường dạng núiOther name:
Herbs, monoecious, perennial, rhizomatous. Rhizome stout, creeping, to 30 cm long, 1–2.3 cm thick, internodes 0.5–1.7 cm long, villous near the petiole insertion. Stipules pale green to pinkish, ovate-triangular, 0.7–1.4 cm long, 0.6–1.3 cm wide, strongly keeled, abaxially hairy along midrib, margin velutinous, apex aristate, arista ca. 0.2 cm long. Petiole red to greenish-purple, terete, 7–20 cm long, 0.4–0.7 cm thick, densely white villous. Leaves alternate, blade asymmetric, ovate to widely ovate, 11.5–19 cm long, 8–13.5 cm wide, broad side 6–8 cm wide, apex acuminate to acute, base strongly oblique-cordate, margin repand to shallowly denticulate and ciliate, thickly chartaceous to succulent, adaxially blackish-malachite green, purplish-olive or dark bluish-brown, with silvery green zone along primary and secondary veins, surface bullate, bulla conical, 0.4–0.8 (−1) cm high, 0.5–0.8 cm across, tipped by 2–4 (−6) peak-like hispidulous protrusions, abaxially pale green, reddish on hollow bullate region, densely brownish-white tomentose on veins; venation palmate with 7–9 primary veins, midrib distinct, 2–4 secondary veins on each side, tertiary veins percurrent or reticulate, sometimes spiderweb-like near petiole attachment, minor veins reticulate. Inflorescences axillary, arising directly from rhizome, dichasial cymes branching 3–8 times; peduncle 11–28 cm long, tomentose to subglabrous; bracts and bracteoles caducous, yellowish-green to reddish, bracts ovate, ca. 1 cm long, 0. 5 cm wide, boat-shaped, abaxially sparsely velutinous along midrib, margin densely tomentose, bracteoles similar to bracts but gradually smaller on upper part of the inflorescence. Staminate flower: pedicel 1.1–2 cm long, tepals 4, outer 2 broadly ovate to obovate-orbicular, 7–12 mm long, 6–10 mm wide, abaxially yellowish-green to reddish, sparsely velutinous, adaxially yellowish to pinkish-green, inner 2 greenish, elliptic, 6–8 mm long, 3–5 mm wide; androecium sub-actinomorphic, spherical, ca. 5 mm across; stamens 55–90; anthers yellow, slightly compressed, obovate, ca. 1 mm long, apex obtuse, filaments fused at base into a column. Pistillate flower: pedicel 1.4–2 cm long, tepals 3, outer 2 suborbicular or broadly ovate, abaxially reddish-green, adaxially yellowish-greenish, 8–12 mm long, 9–13 mm wide, inner 1 yellowish-greenish, elliptic, 5–8 mm long, 2.5–4.5 mm wide; ovary reddish-green, trigonous-ellipsoid, 5–9 mm long, ca. 3 mm thick (wings excluded), sparsely sessile-glandular, 3-winged, wings unequal, reddish-green, lateral wings 2–3 mm wide, abaxial wing crescent-shaped, 3–8 mm wide; styles 3, fused at base, yellow or greenish, ca. 4 mm long, stigma spirally twisted. Capsule trigonous-ellipsoid, 7–11 mm long, 3–4 mm thick (wings excluded), greenish or reddish when fresh; wings unequal, lateral wings 2–4 mm wide, abaxial wing crescent-shaped, 4–9 mm wide. Somatic chromosome number, 2n = 30, 31, 32, 33.
Additional specimens examined
VIETNAM, Thanh Hoa Prov., Ba Thuoc Distr., Co Lung Municipality, Eo Dieu village. Primary evergreen seasonal broadleaved and coniferous submontane forest on crystalline marble-like highly eroded limestone, very steep upper slopes and tops of limestone rocky ridge at elev. 800–850 m. Lithophyte. Introduced from home garden plants in Hanoi for cultivation in Academia Sinica. Specimens pressed from greenhouse plants on 1 April 2013, Ching-I Peng 24610 (HAST); Khuyn village. Primary evergreen seasonal broadleaved lowland forest on crystalline marble-like highly eroded limestone, N slopes of limestone ridge at elev. 400–460 m. Lithophyte on vertical cliff. Occasional. Introduced from home garden plants in Hanoi for cultivation in Academia Sinica. Specimens pressed from greenhouse plants on 22 April 2014, Ching-I Peng 24613 (HAST).
Distribution and ecology
Lithophytic herb on shady cliff. Endemic to Ba Thuoc Dist, Thanh Hoa Province, Northern Vietnam (Figure 3), known only from the type locality. In primary evergreen seasonal broad-leaved closed lowland forest on crystalline marble-like highly eroded limestone, very steep rocky slopes and cliffs at 450–600 m elevation.
The specific epithet refers to the leaf surface with dense conic bullae, which is reminiscent of the peak clusters in Sino-Vietnamese limestone karst landform.