Diplocaulobium aratriferum

Diplocaulobium aratriferum (J.J.Sm.) P.F.Hunt & Summerh., Taxon 10 (1961) 108.

Basionym: Dendrobium aratriferum.

Rhizome short, creeping, branching. Pseudobulbs crowded, 1-leaved, swollen at the base, with a long slender apical part, (2-)7-14.5 cm long, of which the swollen basal part (1-)2 cm long. Leaves lanceolate, (4-)7-9 by 1.5-1.8 cm, base narrowed, apex obtuse, deeply acutely bidentate, rigidly coriaceous. Inflorescences apical, arising in succession, 1-flowered; spathe laterally compressed, 1.5-2 cm long, acute. Pedicel and ovary 4.5-6 cm long. Flower resupinated, c. 9-12 cm across. Dorsal sepal ovate-triangular in basal part, narrowly linear in apical part, 4.5-7 cm by 4.25-5 mm, concave, 5-nerved. Lateral sepals obliquely triangular in basal part, narrowly linear in apical part, 4.5-7 cm by 8.75-9.7 mm, concave, 5-nerved; mentum 0.75 cm long. Petals linear at the base, filiform in apical part, 4.5-7 cm by 2.5-2.7 mm. Lip 3-lobed in apical third, 1.6 by 0.65 cm, with 2 parallel, papillose-pubescent, basal keels extending to the base of the midlobe, the keels somewhat raised between the apices of the side lobes, at the base in between with an indistinct third keel, in the centre of the midlobe with a strongly convex, densely clavate-pilose swelling; lateral lobes erect, short, broadly rounded; midlobe obovate-oblong, 0.8-0.85 by 0.5-0.65 cm, convex, lightly undulate, apical margin more or less irregularly lobulate-crenate, apex broadly rounded, sometimes apiculate, midlobe abaxially concave, keeled, the keel with a porrect tooth just below the apex. Column subconical, 0.4-0.45 cm long, clinandrium 3-lobulate, the lateral lobules triangular, subtruncate, serrate, the median subulate; stigma obovate; column-foot almost at right angles to the ovary, lightly curved, 0.75 cm long. Anther cucullate, flat in front, apex truncate, minutely erose-ciliolate. Pollinia elliptic, lateraly compressed.
(after Smith, 1909).

Colours: Flower white with purplish tips, lip white, on the lateral lobs with transverse dark purple stripes and margins, midlobe pale yellow with scattered dark purple dots.

Habitat: Epiphyte in hill forest and swamp forest. Altitude 0 to 900 m.

Flowering time in the wild: July, August, November.

Distribution: New Guinea (endemic).

Distribution in New Guinea: Papua (Jayapura and Merauke Regencies); Papua New Guinea (widespread).

Notes: Diplocaulobium aratriferum is one of a group of several closely related and at present much confused species. See under Diplocaulobium phalangium.

Cultivation: Intermediate growing epiphyte.