Erect shortly rhizomatous subshrub to 2 m tall. Stems, leaves, and outer surfaces of tepals with a dense covering of long red or white hairs.
Stipules persistent, lanceolate to ovate, 1-3.7 × 0.9-2.4 cm. Leaves: petiole green, 10-40 cm long, joining blade at an angle; blade above green, beneath grayish green, in outline ovate to almost circular, 10-25 × 10-35 cm, usually irregularly five- to eight-lobed, sometimes almost entire, especially in young plants, lobes narrowly to broadly triangular, to 7 cm long, margin of lobes entire, base cordate, veins palmate.
Inflorescence: axillary, short, 12-22-flowered, bisexual, cymose; bracts soon falling, broadly elliptic to obovate, 0.6-2.5 × 0.2-1 cm.
Male flowers: tepals four, white to pink, outer pair broadly elliptic, 0.8-1.6 x 0.7-1.2 cm, inner pair elliptic, 0.7-1.7 × 0.5-0.9 cm; stamens 65-75, arranged symmetrically, anther connectives projecting.
Female flowers: bracteoles absent,; tepals five, white to pink, elliptic to obovate, 0.9-2 × 6.5-1.1 cm; ovary fleshy, green, almost spherical, 0.7-1.5 cm in diameter, unequally 3-winged, one wing much longer than others, three-locular, placentae axile, bifid; styles three, once branched, stigmas in spiraled band. (Tebbitt, M.C., Begonias: Cultivation, Identification, and Natural History. 2005)
Chromosome Numbers
2n = 88. (Tebbitt, M.C., Begonias: Cultivation, Identification, and Natural History. 2005)
Habitat
Rainforests, 1100-2600 m asl.
Conservation
Proposed IUCN category: LC. Widespread. (Hughes, M. An annotated checklist of Southeast Asian Begonia. 2008)
Distribution
Asia-Tropical:, Jawa (Jawa); Lesser Sunda Is. (Lesser Sunda Is.); Sulawesi (Sulawesi); Sumatera (Sumatera)
Indonesia: Sumatra, Java, Lesser Sunda Isles (Bali), Sulawesi.
See Specimens tab for map of point distribution data of georeferenced specimens.
Notes
At their most "typical" form, B. robusta may be distinguished from B. multangula thus (Tebbitt, 2005): - B. robusta: Leaf blades above with long red glandular hairs, margin entire or with short rounded lobes; peduncle of infructescence usually at least four times longer than the pedicels; fruit usually with one longer wing and two shorter wings or ribs. - B. multangula: Leaf blades glabrous above or with short to long white or red glandular hairs, margin with several short angular lobes; peduncle of infructescence usually less than three times as long as the pedicels; fruit with three equal ribs or short thickened wings. However, many intermediate (possibly hybrid) specimens exist. (Hughes, M. An annotated checklist of Southeast Asian Begonia. 2008)