Dendrobium vannouhuysii J.J.Sm., Bull. Dép. Agric. Indes Néerl. 45 (1911) 6; Nova Guinea 8, 3 (1911) 573, t. 95A.
Type: Nouhuys, van s.n. (Treub Mountains) (holo BO).
Rhizome creeping. Stems 2.7-3.5 cm by 1.8 mm, internodes 0.2-0.3 cm long. Leaf sheaths tubular, with 5 prominent, subrugulose ribs. Leaves patent, ovate to oblong-ovate, 0.3-0.8 by 0.27-0.43 cm, carnose, concave above, margins at the apex papillose-ciliolate, apex acutely acuminate. Inflorescences terminal, erect, very short; peduncle 0.2 cm long, peduncle-scales short, broadly triangular, tubular at the base, keeled, slightly verrucose, acute, 1-, sometimes 2-flowered. Floral bracts broadly obtuse, apiculate. Pedicel and ovary 3.2 cm long. Flowers very large for the plant, c. 3.5 cm long. Dorsal sepal obovate, 1.25 cm by 7.5 mm; mentum 2.15 cm long, entirely open in front, apex narrowly obtuse. Petals spathulate, 1.2-1.3 cm by 5.5-5.8 mm. Lip clawed, cuneate, when flattened 2.25 by 1.67 cm, base for 1.8 cm adnate to the column-foot, apex very broadly bilobulate, cucullate, margins minutely erose. Column 0.4 cm long, stelidia broadly triangular, obtuse, with an additional pair of subulate stelidia next to the stigma; column-foot 2.15 cm long.
(after Smith, 1911 & 1913).
Colours: Sepals and petals bright (orange-)red, lip yellow, rarely whole flower pale yellowish.
Habitat: Terrestrial in open montane vegetation (e.g. old landslides) and on mossy cliffs. Altitude 2000-3300 m.
Flowering time in the wild: January, October.
Distribution: New Guinea (endemic).
Distribution in New Guinea: Papua (Jaya Wijaya Regency); Papua New Guinea (Enga Province).
Notes: Dendrobium vannouhuysii is one of the most distinctive and charming of all New Guinea dendrobiums. The flowers appear disproportionally large for such a small plant. In the Calyptrochilus group it is one of the few species with widely opening flowers, like Dendrobium apertum, Dendrobium nubigenum, Dendrobium purpureiflorum, and Dendrobium chrysopterum. Dendrobium vannouhuysii, with its finger-tall stems and tiny leaves is totally different in habit from any of these.
Cultivation: Difficult. Dendrobium vannouhuysii requires cool and very humid conditions, but at the same time bright light and plenty of fresh air.