Diplocaulobium nitidissimum

Diplocaulobium nitidissimum (Rchb.f.) Kraenzl., in Engl., Pflanzenr. IV. 50. II. B. 21 (1910) 337.

Basionym: Dendrobium nitidissimum.

Rhizome creeping. Stems of two types: those with relatively short pseudobulbs that do not flower, and long slender stems that do. Pseudobulbs 0.5-1.5 cm apart, 1-leaved, ovoid-fusiform to narrowly conical, 1.6-4.5 by 0.6-1.4 cm, at apex 0.2-0.4 cm diameter, flowering stem 1-leaved, 20-35 cm long, in lower 2-4 cm slightly swollen, 3-4 sided. Leaves on pseudobulbs linear, 8-12 by 0.9-1.2 cm, thin coriaceous, apex acute, equally or unequally bilobulate; leaves on flowering stem much smaller, lanceolate, 2-3 by 0.6-0.7 cm, apex rounded, (deeply) bilobulate. Inflorescences terminal, 1-flowered, in fascicles of up to 4 flowers; peduncle 2.5 cm long; spathe oblong, 1.4-2.5 by 0.3 cm. Pedicel and ovary 2-3 cm long, cylindrical. Flower 4-6 cm across, ephemeral. Dorsal sepal suberect, narrowly triangular, base sometimes lanceolate, 3-3.8 cm by 3 mm, concave, apex acute. Lateral sepals narrowly triangular, 3-3.8 cm by 5-7 mm, apex acute; mentum inflated-conical, 5 mm long. Petals suberect to recurved, linear, base sometimes oblong, 2.8-3.5 cm by 1 mm, apex acute. Lip 3-lobed near the middle, 1.2-1.5 by 0.5 cm, with two straight basal keels which are hairy at the base and become undulating on the claw of the midlobe where they terminate in a cushion-shaped, glandular-hairy callus; lateral lobes erect, free part broadly triangular, front margin erose, apex acute; midlobe slightly decurved, spathulate or ovate with a narrow claw, margins undulating, apex variable, from entire to apiculate to tridentate. Column 0.4 cm long, stelidia short, bidentate; column-foot 0.5 cm long, at right angles to the column proper, slightly incurved. Fruit cylindrical-obovoid, approximately 5-sided, 1.7 by 0.5 cm.
(after O'Byrne, 1994).

Colours: Sepals and petals pure white with pale yellow tips. Lip creamy white with a bright yellow midlobe, lateral lobes purple-spotted with purple margins, keels and callus yellow. Flowers turn lilac just before they close.

Habitat: Epiphyte in coastal forest and lowland rainforest. Altitude 0-125 m.

Flowering time in the wild: July, October-February. Flowers last only a few hours and are produced 8 days after heavy rainfall (fide O'Byrne).

Distribution: Admiralty Islands, Bismarck Archipelago, ?Solomon Islands.

Distribution in New Guinea: Papua New Guinea (Manus Island, New Britain, New Ireland).

Notes: Diplocaulobium nitidissimum is a remarkable and easily recognised species because the plants produce two entirely different types of stem: stems with relatively short pseudobulbs, and much taller and very slender stems only slightly swollen at the base. Only the tall stems, which have much smaller leaves than the short ones, are capable of flowering.

Cultivation: Warm growing epiphyte.