Dendrobium mussauense

Dendrobium mussauense Ormerod, Austral. Orchid Rev. 62, 3 (1997) 13, fig.

Type: Koie & Sandermann Olsen 1293 (holo LAE, iso C).

Rhizome, roots and lower part of stem not seen. Stem ca. 1.5 m long by 1-1.5 cm thick, laxly 10-15 leaved. Leaves oblong-elliptic, to 14 by 6 cm, unequally and weakly obtusely bilobed, apiculate, coriaceous. Inflorescences stoutly erect, 1-2 arising from upper part of stem, to 34 cm long, sublaxly c. 15-flowered. Floral bracts ovate, to 6 mm long, acute. Pedicel and ovary to 4.5 cm long. Flowers widely opening. Dorsal sepal obliquely erect over column, usually half twisted, oblong-ligulate, 2.5 cm by 6-7 mm, obtuse, 5-7 nerved. Lateral sepals spreading, oblong, widening towards mentum, 2.5 cm by 6-7 mm midway, 12-13 mm broad at base, subacute; mentum conical, deflexed apically, 1.2-1.3 cm long. Petals more or less erect, once to twice twisted, oblanceolate-spathulate, 3-3.5 cm by 7-l0 mm, 2 mm broad at base, obtuse-subacute, 5-7 nerved. Lip 3-lobed, 3-3.2 cm by 20 mm across apices of lateral lobes; callus of five lamellate keels, the central three most prominent, but all five dilated and more or less undulate on disc of midlobe; lateral lobes elliptic, unevenly truncate; midlobe quadrate, emarginate, margins more or less undulate, 12 mm long and broad. Column 7 by 4 mm, stelidia truncate.
(after Ormerod, 1997).

Colours: Flowers faint yellow, the lip white with purple veins.

Habitat: Epiphyte. Altitude not recorded (close to sea level).

Flowering time in the wild: Not known.

Distribution: New Guinea (endemic).

Distribution in New Guinea: Papua New Guinea (Bismarck Archipelago, island near Mussau Island).

Map: MUSSAMAP.JPG [Dendrobium mussauense Ormerod, distribution map.]

Notes: Dendrobium mussauense is closely related to Dendrobium lineale but has a broader lip (20 mm versus 16 mm), a quadrate not oblong midlobe and five distinct keels on the lip instead of three.

Dendrobium wulaiense Howcroft is another similar species, it may be distinguished from D. mussauense by its relatively smaller obovate midlobe and bidentate column stelidia. The form of Dendrobium gouldii with white flowers and violet-striped lip may also be confused with D. mussauense but the former has a subspathulate to rhombic midlobe on which the keels terminate in elevated triangular flaps.
(after Ormerod, 1997).

Cultivation: Warm growing epiphyte.