Volume 14 > Part 3 > Year 2019 > Page 362 > Begoniaceae > Begonia

1. Begonia acetosella Craibwfo-0000823241

[§ Platycentrum], Bull. Misc. Inform. Kew 1912: 153. 1912; Gagnep., Bull. Mus. Hist. Nat. (Paris) 25: 282. 1919; Irmscher, Mitt. Inst. Allg. Bot. Hamburg 6: 347. 1926; Craib, Fl. Siam. 1: 770. 1931; Tebbitt, Brittonia 55. 1: 22. 2003; Hughes, Annot. Checkl. SE Asian Begonia. 1. 2008. Fig. 1. Plate XXXIII: A–B.

Accepted Name : This is currently accepted.

Synonyms & Citations :

Description : Dioecious caulescent herb, up to 2 m tall. Stems rhizomatous with numerous fibrous roots, aerial stem erect, dark red, covered with few minute brown hairs, internodes up to 20 cm long, succulent, 5−7 mm diam. Leaves alternate; petiole dark red, 2−10 cm long, glabrous or with sparse glandular hairs; lamina basifixed, succulent, strongly asymmetric, chartaceous when dry, adaxial surface glabrous, dull dark green, abaxial surface sparsely hairy, pale green or tinged pink on veins; oblong-lanceolate to ovate-lanceolate, 10−20 by 4−10 cm, base unequal and slightly truncate, apex acuminate, margin serrate or slightly biserrate, venation palmate-pinnate, midrib and lateral veins concolourous with lamina, veins 5–7, prominent beneath. Stipules caducous, pale green, lanceolate to ovate-lanceolate, 10−15 by 5−6 mm, apex acute, margin entire. Inflorescences axillary (male inflorescence 3−6 cm long, female inflorescence 0.5−1 cm long), dichasium; peduncles dark red, terete, glabrous, glossy. Bracts caducous, pale green, ovate, 5−10 by 1−3 mm, membranous, apex acute, margin entire. Staminate flowers: pedicels dark red, 5−7 mm long, with a few minute glandular hairs; tepals 4, white or flushed pink at base, outer 2 ovate to obovate, 10−17 by 5−16 mm, base rounded, apex rounded, margin entire, glabrous on both sides, inner 2 obovate, 6−8 by 3−6 mm, base cuneate, apex acute, margin entire, glabrous on both sides; androecium actinomorphic, subglobose, stamens 60−95, strongly pale yellow, filaments free ca 2 mm long, anthers 1.5–2.5 mm long, rectangular, dehiscing by vertical slits near tip. Pistillate flowers: pedicels pale dark red, 2−6 mm long; tepals 4, unequal, creamy white, rounded to orbicular, outer 2, 6−8 by 6−10 mm, inner 2, 6−7 by 3−7 mm, base obtuse, apex rounded, margin entire, glabrous on both sides; styles 4, fused at base, yellow, stigmatic band kidney-shaped, twice spirally twisted; ovary 4-locular with a short horn-like wing on central part of each, placentae bilamellate. Fruit a fleshy berry, pendulous, light green, drying brown, rhomboidal to spherical, 10−15 by 14−17 mm, wings horn-like, triangular, to 6 mm long, base 4−5 mm. Seeds dark brown, barrel-shaped.

Thailand : NORTHERN: Chiang Mai (Doi Suthep – type: Kerr 557, lectotype -K, isolectotypes -B K), Chiang Rai, Nan, Phrae; EASTERN: Chaiyaphum; NORTH-EASTERN: Loei.

Distribution : Myanmar, Laos, Vietnam, China.

Ecology : On wet soil in dry evergreen forests with bamboo or hill evergreen forests, 600–2,000 m alt. Flowering: June–September; fruiting: November–December.

Vernacular : Som kung bok (ส้มกุ้งบก).

Notes: Begonia acetosella Craib is a dioecious species, and the tallest species in Thailand. Vegetatively it looks much like B. longifolia Blume, however the latter differs in having a 3-locular ovary and is monoecious.