Orchids of New Guinea

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Dendrobium ostrinum

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).Gjellerup 444 (holo BO).

Synonyms:

Grastidium ostrinum (J.J.Sm.) M.A.Clem. & D.L.Jones, Lasianthera 1 (1997) 95.

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.
Flower creamy white, lip and column lightly sulphur yellow, apex of mentum salmon-coloured.

Habitat:

Epiphyte in lowland forest.
Epiphyte in lowland and hill forest. Altitude to 200 m.

Distribution:

New Guinea (endemic).
New Guinea (endemic).

Distribution New Guinea:

Papua (Merauke RegencyPapua (Puncak Jaya and Jayapura Regencies); Papua New Guinea (East Sepik Province).

Map: Dendrobium ostrinum J.J.Sm., distribution map.

Cultivation:

Warm growing epiphyte.
Warm growing epiphyte.

Flowering time in the wild:

October.
March, July-September.

Classification:

Family Orchidaceae
Subfamily Epidendroideae
Tribe Dendrobieae
Subtribe Dendrobiinae
Genus Dendrobium
Section Grastidium
Species Dendrobium ostrinum

Literature:

O'Byrne, P. 1994. Lowland Orchids of Papua New Guinea: 334, fig.

Notes:

INFRASPECIFIC TAXA

Dendrobium ostrinum J.J.Sm. var. ochroleucum J.J.Sm., Nova Guinea 12, 1 (1913) 51.

Synonym: Grastidium ochroleucum (J.J.Sm.) M.A.Clem. & D.L.Jones, Lasianthera 1 (1997) 94

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.

Dendrobium ostrinum J.J.Sm. var. ochroleucum J.J.Sm. differs from the typical variety in the creamy-white flowers and the denser tuft of spine-like hairs on the midlobe of the lip.