B. khammouanensis

Culture

Endangered Status

IUCN category VUD2, known only from 2 locations

Original Botanical Description or Link to

Two new species of Begonia L. (Begoniaceae) from central Laos Keooudone SOUVANNAKHOUMMANE, Soulivanh LANORSAVANH, Vichith LAMXAY: Begonia khammouanensis Souvann. & Lamxay, sp. nov. Som Koung Bai Boua [Lotus leaf begonia] Sect. Diploclinium. A distinct species, closest to Begonia crassula Aver. in having succulent leaves, the same number of tepals in male and female flowers and bifid, axile placentae. It differs in being stemless (not succulent caulescent), and in having a symmetric reniform lamina, (not strongly asymmetric and narrowly ovate), and lanceolate and acuminate apex of tepals (not reniform and rounded apex of tepals). − Type: Laos, Khammouan province, Boualapha district, Hin Nam No National Protected Area, 17°26'35.6"N 105°47'30.2"E, 259 m,, 10 October 2017, Lamxay et al. HNN 138 (holo HNL, iso FOF, E, SING). Monoecious rhizomatous herb, 30–50 cm tall. Rhizomes stout, 3–12 cm long, 6–10 mm in diam., erect near apex, c. 2 cm tall, with numerous fibrous roots. Leaves arranged in rosette-like cluster at the top of rhizome; petiole 5–24 cm long, puberulous to glabrescence, dark red at base, paler red-green toward apex; lamina succulent, symmetrical, reniform, 4–6.5 × 6–8.6 cm, base shallowly cordate, apex rounded, margin undulate; adaxial surface, glossy, dark green, abaxial surface pale green, glabrous on both surface; venation palmate, veins 5–7, prominent beneath. Stipules persistent, herbaceous, ovate to triangular-cuneate, 14– 25 × 6–12 mm, apex acute to acuminate, margin entire, outside puberulous, inside glabrous, pink to lightly green. Inflorescences compound cymes arising from top of rhizome, branched up to 4 times, bisexual, 35–40 cm long, staminate flowers distal and pistillate flowers basal, protandrous; peduncles 20–36 cm long, terete, with glandular hairs, dark red, glossy. Bracts ovate, 3–8 × 2–4 mm, apex acute, margin entire, glandular hairy outside, pale green. Staminate flowers: pedicels 10–12 mm long, erect or occasionally ascending, sparsely glandular hairy, dark red; tepals 2, lanceolate, 14–16 × 6–10 mm, apex acuminate, outside surface with glandular hairs, inside surface glabrous, pink flush inside and outer part darker; stamens c. 15, bright yellow, filaments clustered at the base, c. 2.5 mm, free 0.7–1 mm long, anthers oblong-elliptic, 0.8–1 mm long, dehiscing by longitudinal slits near the tip. Pistillate flowers: pedicels 12–18 mm long, with glandular hairs, dark red; tepals 4, outer 2 lanceolate, 12–15 × 8–12 mm, margin entire, apex acuminate, outside surface sparsely glandular hairy, inner 2 elliptic-lanceolate, 6–9 × 3–6 mm, margin entire, apex acuminate, glabrous, same colour as staminate flowers; ovary lightly red or pink, with 3 locular, with 3 wings, abaxial one narrowly rectangular, lateral 2 small ridges; 3-locular, placentation axillary, 2 branches per locule; styles 3, connate at the base into common stalk, dark yellow; stigmatic band U-shaped and minutely papillose;. Fruits capsules, elliptic-oblong, 12–15 × 7–12 mm (including wings); locules subglobose, 3–4 × 3–4 mm, abaxial wing narrower, narrowly rectangular, curved along length of capsule, c. 14 mm long, 3.5–4 mm wide, 2 lateral wings reduced to ridges, wide at base, glossy, with glandular hairs, pale red to pink, drying pale brown. Seed numerous, elliptic-oblong, 0.3–0.4 × c. 0.1 mm, testa reticulate, brown. Distribution. Endemic to central Laos; Hin Nam No National Protected Area with three additional populations in Boualapha district, Khammouan province. Habitat and ecology. This species occurs on wet steep rocky slopes in limestone mixed deciduous forest and dry evergreen forest at 230-400 m elevation. Flowering September to October; fruiting October to January. Notes. This species is distinct in its glabrous and glossy symmetrical reniform lamina, and petioles and inflorescences with glandular hairs. The specific epithet khammouanensis refers to the type locality. Proposed IUCN category. VU D2. This new taxon is only known from two locations in very limited area and few populations.