Dendrobium forbesii Ridl., J. Bot. 24 (1886) 323.
Type: Forbes 634 (syn BM); Barclay s.n. (Jobi I.) (syn BM).
A large epiphytic herb. Pseudobulbs clustered, clavate, up to 32 by 1.6-2.5 cm, 4-6-noded below leaves, orange when dry, 2-leaved at apex. Leaves coriaceous, spreading, elliptic or oblong-elliptic, obtuse or rounded at apex, 9-19 by 4.7-11 cm, shortly and broadly petiolate. Inflorescence erect, apical, 15-30 cm long, 7-20-flowered; peduncle almost covered by large inflated pale green sheaths; bracts large, lanceolate, acuminate or acute, up to 3.8 by 1.3 cm. Flowers large, attractive; pedicel and ovary setose, 4 cm long. Dorsal sepal lanceolate, acuminate, 2.7-3.2 by 1 cm, scarcely hairy on outer surface; lateral sepals obliquely lanceolate, acuminate, 3-3.6 by 1.2-1.6 cm, almost glabrous but with broad lacerate keels on mid vein; keel 2-3 mm broad; mentum incurved-conical, 1-1.3 cm long. Petals obovate-spathulate, apiculate, 3-3.5 by 1.6-2.3 cm, margins undulate. Lip 3-lobed, 2-2.6 by 2.7-3 cm; side-lobes smaller than midlobe , erect, oblong, truncate; midlobe transversely oblong with a triangular apical lobule; callus 3-ridged, with a 4 mm long free apex. Column short, 2.5 mm long, somewhat erose at apex; foot incurved, 1-1.2 cm long.
(after Cribb, 1983).
Colours: Flowers pure white or creamy white sometimes with purple on side lobes of lip.
Habitat: Epiphyte in montane forest. Altitude 900-1500 m.
Flowering time in the wild: October to December.
Distribution: New Guinea.
Distribution in New Guinea: Papua New Guinea (Central Highlands and Northern mountain ranges, including the Torricelli Mountains).
Map: FORBEMAP.JPG [Dendrobium forbesii Ridl., distribution map, redrawn from P. Cribb, Kew Bull. 38 (1983) 234, map 2.]
Notes: Dendrobium forbesii is readily recognised by its broad petals, sepals which are almost glabrous and lateral sepals with a broad lacerate keel on the mid-vein.
(after Cribb, 1983).
Cultivation: Intermediate growing epiphyte.