Dendrobium ostrinum J.J.Sm., Bull. Dép. Agric. Indes Néerl. 39 (1910) 10; Nova Guinea 8, 3 (1911) 556, t. 90A.
Type: Römer, von 568 (syn BO); Bogor cult. (Rachmat) 415 (syn BO).
Stems elongated, flexuose, in cross-section elliptic, up to at least 40 cm by 3.6 mm, internodes 3.5-5 cm long. Leaf sheaths tubular, when dry ribbed and transversely rugose, with an obtuse tooth opposite the leaf-blade. Leaves oblong to lanceolate, 5.5-7 by 1.85-2 cm, carnose, midvein obtusely prominent below, above on either side of the midvein conspicuously convex, base obtuse, apex obtuse, more or less unequally bilobed. Inflorescences arising laterally from the stem, short, 2-flowered; spathe very short. Pedicel and ovary 0.55 cm long, obconical, 6-grooved. Flowers c. 1.6 cm wide, ephemeral, with the sepals and petals incurved. Dorsal sepal lanceolate, 1.65 cm long, 7-9-nerved, apex acute. Lateral sepals lanceolate, falcate, 1.65 cm by 6 mm, concave, 7-9-nerved, keeled outside, apex acute. Petals lanceolate, falcate, 5-7-nerved, apex acute, almost acuminate. Lip 3-lobed above the middle, 0.74 by 0.6 cm, erect, curved, concave, with a high, flattened basal keel extending to the base of the midlobe, on either side at the base of the keel with a verrucose callus, elsewhere below the midlobe transversely lamellate inside, on the base of the midlobe with several narrow erect elongated lamellae; lateral lobes clasping the column, obliquely sublinear, 0.28 by 0.1 cm, apex dentate to lacerate; midlobe triangular, 0.34 by 0.4 cm, margins lacerate, apex obtusely acuminate. Column conical, 0.33 cm long, clinandrium 3-lobulate, the lateral lobules obtuse, concave, the median subulate; stigma elliptic; column-foot at almost right angles to the ovary, 0.3 cm long, almost straight, truncate. Anther cucullate, in front flat, apex truncate, minutely erose, 1.3 mm wide. Pollinia oblong.
(after Smith, 1911).
Colours: Flower purple-violet, keel on the lip orange, column-foot white, at the apex with an orange spot.
Habitat: Epiphyte in lowland forest.
Flowering time in the wild: October.
Distribution: New Guinea (endemic).
Distribution in New Guinea: Papua (Merauke Regency: Lorentz River).
Map: OSTRIMAP.JPG [Dendrobium ostrinum J.J.Sm., distribution map.]
Cultivation: Warm growing epiphyte.
INFRASPECIFIC TAXA
Dendrobium ostrinum J.J.Sm. var. ochroleucum J.J.Sm., Nova Guinea 12, 1 (1913) 51.
Type: Gjellerup 444 (holo BO).
Leaves 4-7 by 1.45-2.25 cm. Dorsal sepal 2 by 0.46 cm; mentum 0.5 cm long. Petals 1.8 by 0.37 cm. Lip when flattened 0.98 by 0.75 cm.
Colours: Flower creamy white, lip and column lightly sulphur yellow, apex of mentum salmon-coloured.
Habitat: Epiphyte in lowland and hill forest. Altitude to 200 m.
Flowering time in the wild: March, July-September.
Distribution: New Guinea (endemic).
Distribution in New Guinea: Papua (Puncak Jaya and Jayapura Regencies); Papua New Guinea (East Sepik Province).
Notes: Differs from the typical variety in the creamy white flowers and the denser tuft of spine-like hairs on the midlobe of the lip.
Cultivation: Warm growing epiphyte.