Dendrobium apertum Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 518; 21 (1923) t. 176, fig. 656.
Type: Schlechter 18593 (holo B, lost; iso BO, E, G, K, L, NSW).
Rhizome very short, roots elongated, filiform, flexuose, glabrous. Stems crowded, patent, slender, up to 50 cm long, densely many-leaved, branching. Leaf sheaths entirely covering the stem. Leaves patent, elliptic to elliptic-ligulate, 1.5-3 by 0.55-1 cm, apex aristate-apiculate. Inflorescences racemose, very short, 3-5-flowered. Floral bracts ovate, much shorter than the pedicel and ovary, apex aristate-apiculate. Pedicel and ovary 2.2 cm long, slender, glabrous. Flowers resupinated or not, c. 2.5 cm long. Dorsal sepal elliptic, 1.1 cm long, apex obtuse. Lateral sepals obliquely elliptic, much widened at the base, 1.1 cm long, apex obtuse; mentum subcylindrical, 1.4 cm long, obtuse, slightly curved, open in front. Petals obliquely oblong-subspathulate, 1.1 cm long, apex obtuse. Lip concave, with a narrow ligulate claw, slightly widened towards the apex, 1.8 cm long, 0.35 cm wide across the claw, near the apex 0.6 cm wide, apical margin pectinate-denticulate, 5-plicate, apex hood-like, obtuse. Column short, clinandrium 3-lobulate, lateral lobules rounded-truncate, the median tooth-like; column-foot linear, 1.8 cm long, entirely adnate to the margins of the lip, near the apex with a decurved appressed tooth. Anther quadrate-cucullate, subretuse at the back, in front truncate and papillose.
(after Schlechter, 1912).
Colours: Flower pink or red.
Habitat: Epiphyte in lower montane forest. Altitude 1200-1800 m.
Flowering time in the wild: May-November.
Distribution: New Guinea (endemic).
Distribution in New Guinea: Papua (Jaya Wijaya Regency); Papua New Guinea (Western Highlands, Eastern Highlands, Madang, and Morobe Provinces).
Notes: Dendrobium apertum may be recognised by the widely opening flowers and by the patent leaves which at the apex are drawn out in a conspicuous point.
Cultivation: Intermediate growing epiphyte.