Dendrobium riparium J.J.Sm., Repert. Spec. Nov. Regni Veg. 12 (1913) 117; Nova Guinea 12, 3 (1916) 343, t. 124, fig. 227.
Type: Gjellerup 1099 (holo BO).
Stems stout, elongated, branching, angular-terete, in upper part flexuose, 90 cm long, internodes to 4.3 cm long, shorter in upper part. Leaf sheaths verrucose. Leaves patent, lanceolate, 2-4.4 by 0.7-1.35 cm, thin coriaceous, apex subunequally obtuse to acute, slightly apiculate. Inflorescences lateral from defoliated branches, very numerous, racemose, very short; rachis 1-1.2 cm long, densely to c. 12-flowered. Floral bracts triangular, 0.8 by 0.45 cm, apex acuminate, outside verruculose. Pedicel and ovary 2.5 cm long, clavate, obtusely triangular in cross-section. Flowers 2.5 cm long. Dorsal sepal 0.9 cm by 5.7 mm; mentum subcylindrical, 1.5 cm long, obtuse. Petals 0.85-0.88 cm by 3.5 mm. Lip clawed, spathulate, when flattened 1.8 by 0.9 cm, claw for 1.1 cm adnate to the column-foot; apex cucullate, plicate, apical margin densely shortly subulate-laciniate. Column 0.28 cm long; column-foot 1.4 cm long.
(after Smith, 1911).
Colours: Flower bright orange.
Habitat: Epiphyte on shrubs and on trees in montane forest. Altitude 1900 m.
Flowering time in the wild: April.
Distribution: New Guinea (endemic).
Distribution in New Guinea: Papua (Manokwari Regency: Arfak Mountains).
Notes: Dendrobium riparium seems hardly different from Dendrobium subclausum.
Cultivation: Cool growing epiphyte.