Dendrobium keytsianum J.J.Sm., Repert. Spec. Nov. Regni Veg. 12 (1913) 115; Nova Guinea 12, 3 (1916) 347, t. 126, fig. 231.
Type: Cock d'Armandville, le 246 (holo BO).
Stems elongated, terete, internodes 1.3-2 cm long. Leaf sheaths verruculose in apical part. Leaves patent, narrowly linear-lanceolate, 9.75-10 by 1-1.2 cm, papyraceous-coriaceous, margins near apex minutely fimbriate, apex narrowly obtuse, mucronate. Inflorescences lateral from defoliated stems, racemose, very short; rachis 0.7-0.8 cm long, c. 3-flowered. Floral bracts broadly ovate-triangular, 1 cm long, apex acuminate, outside verruculose. Pedicel and ovary 2.65 cm long, clavate, obtusely triangular in cross-section. Flowers 3.5 cm long. Dorsal sepal 1.4 cm by 8.5 mm; mentum conical, 2.1 cm long, obtuse. Petals 1.4 cm by 5 mm. Lip clawed, spathulate, when flattened 2.7 by 1.47 cm, claw for 1.55 cm adnate to the column-foot, at c. 0.95 cm above the base with a V-shaped thickening; apex cucullate, plicate, apical margin densely narrowly serrate. Column 0.5 cm long; column-foot 2.1 cm long, at the apex with a short cavity and a small tooth-shaped lamella.
(after Smith, 1916).
Colours: Flowers orange and yellow.
Habitat: Epiphyte, presumably in montane forest. Altitude 1900 m.
Flowering time in the wild: December.
Distribution: New Guinea (endemic).
Distribution in New Guinea: Papua (Jaya Wijaya Regency).
Notes: Dendrobium keytsianum appears to belong in the alliance of Dendrobium subclausum, but with larger flowers than usual and with a V-shaped thickening on the lip, which is not normally found in D. subclausum.
Cultivation: Cool growing epiphyte.