Begonia rajah Ridl. ex Rolfe

Tan, Joanne Pei-Chih, Tam, Sheh May & Kiew, Ruth, 2018, Begonia yenyeniae (Begoniaceae), a new species from Endau Rompin National Park, Johor, Malaysia, PhytoKeys 110, pp. 23-37 : 23

Begonia rajah Ridl. ex Rolfe Figure 1 , 3

Gardeners’ Chronicle XVI (1894) 213, nom. nud.; Rolfe, Bulletin of Miscellaneous Information (1914) 327; Irmscher, Mitteilungen aus dem Institut für allgemeine Botanik in Hamburg 8 (1929) 96; Tebbitt, Begonias: Cultivation, Identification, and Natural History (2005) 198; Kiew, Begonias of Peninsular Malaysia (2005) 216, pro parte.

Section.

Jackia M.Hughes

Type.

Peninsular Malaysia. Terengganu, 1892, Native collector s.n. (holotype SING ex K!). Description. Dwarf herb with rhizomatous stem. Indumentum of soft hairs, usually pale pink, dense on stipule (1.5-2 mm long), petiole (cream-coloured, 2-4 mm), leaf margin (1-1.5 mm) and veins beneath (2-2.5 mm), peduncle (cream-coloured, 2-2.5 mm). Stems creeping, ca. 9 mm thick, light yellowish-green; stipules lanceolate-oblong or triangular, 15-20 × 6-10 mm, apex attenuate terminating in a hair, keeled from base to apex, margin entire and opaque, brownish-pink to scarlet, persistent. Leaves tufted, alternate, ca. 5 mm apart; petioles suberect, terete, ca. 5 mm across, 8-25 cm long, light yellowish-pink; blades rigid, succulent, glabrous, broadly ovate with an abruptly acute apex or radical oblique cordate, 7-15 × 6-15 cm, prominently bullate, margin ciliate, angular with abruptly acute teeth, basal lobes cordate, slightly overlapping when mature, notably dark brownish-purple blotches, polished shining surface, young blades brownish-pink to vivid brownish-red, paler beneath; veins palmate, prominent towards the base and slightly impressed near margin, prominent beneath, lateral veins ca. 1-3 pairs, greenish-yellow when young, yellowish-green when mature. Inflorescences axillary, almost erect, many-flowered cyme, 20-25 cm long, peduncles 7-12 cm long, brownish-pink, two main branches ca. 1.3 cm long, pedicels slender, ca. 1 cm; bracts in pairs at node of peduncle, glabrous, broadly ovate, bowl-shaped, subacute, margin laciniate 5-8 × 7.5-8 mm, light yellowish-pink, persistent; bracteole narrowly ovate, 2-3 mm long, pale yellowish-pink. Male flowers with 4 tepals, margin entire, ca. 1.8 cm across, rose pink; outer tepals 2, obovate-orbicular or elliptic-ovate, 6-8 × 5-8 mm, inner 2 tepals obovate or narrow oblong, apex rounded or sometimes retuse and impressed along centre, ca. 5 × 3 mm; stamen mass globose, symmetric, 3 × 2.5 mm; anthers broadly obovoid-oblong, tip rounded, ca. 0.7 mm long, dehiscing through 2 longitudinal slits. Female flowers with a pale pink ovary with darker pinkish margin, 7-8 mm, locules 3, placentation axile, 1 placenta per locule, each placenta usually with 2 minute branches at the base, usually 3 tepals rarely 2, outer 2 tepals widely elliptic-ovate, concave at centre, ca. 6-7 mm, pale pink; styles and stigmas 3, 2-2.5 mm, style light greenish-yellow, stigma pale yellow, papillose, spiral band. Capsules ca. 1.2 cm across, locules 3, splitting longitudinally between locules, surface glabrous, dangling on a fine, thread-like pedicel 1 cm long. Seeds not seen by us.

Distribution.

Endemic in Peninsular Malaysia, Terengganu (without specific locality). Apparently restricted in its distribution because, despite continuous botanical collecting in Terengganu and elsewhere in Peninsular Malaysia, it has not been re-found since it was first collected in 1892 (Kiew, 2005).

Etymology.

From a Sanskrit word raja = king, presumably referring to it as the most beautiful begonia species.

Conservation status.

Extinct in the Wild (EW). However, it survives in cultivation since its first introduction into cultivation in 1894 ( Anonymous 1894b, 1895).

Ecology.

Its natural habitat is not known but judging from its growth requirements in cultivation, it probably grew in cool and shaded conditions. Other specimens examined. Peninsular Malaysia. Herbarium specimens made from cultivated plants in Royal Botanic Gardens, Kew Anonymous s.n. 1903 (K!); Sander F. et al., s.n. 1913 (K!); Anonymous s.n. August 1913 (K!).

Figures

Figure 1. Watercolour painting of Begonia rajah of an original wild-collected plant grown in the Botanic Gardens, Singapore. (Reproduced with permission of the Singapore Botanic Gardens)

Figure 3. Begonia rajah Ridley (cultivated) A Upper leaf surface B under surface C Young blade.