Orchids of New Guinea

Prev Taxon: Genus Dendrobium section Diplocaulobium subsection Mekynosepalum

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Dendrobium auricolor

Dendrobium auricolor J.J.Sm., Bull. Dép. Agric. Indes Néerl. 45 (1911) 3; Nova Guinea 8, 3 (1911) 549, t. 87D.

Type: Bogor cult. (Branderhorst) 223 b (holo BO).

Synonyms:

Diplocaulobium auricolor (J.J.Sm.) A.D.Hawkes, Lloydia 20 (1957) 127.
Dendrobium auricolor J.J.Sm. var. major Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 476; 21 (1923) t. 161
Dendrobium auricolor J.J.Sm. var. minor Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 476; 21 (1923) t. 161
- Type: Schlechter 16685 (holo B, lost).
Dendrobium auricolor J.J.Sm. var. cyclopense J.J.Sm., Nova Guinea 12
- Type: Gjellerup 518 (holo BO).

Rhizome short. Pseudobulbs crowded, 1-leaved, at the base fusiform, with a much longer very slender upper part which is angular-subterete basally, in apical part slightly widened, transversely elliptic in cross-section, ribbed, 40-50 cm long, the swollen base 3.5-4 cm long, at the base 12-15 mm wide, in the middle 3-3.3 mm wide, at the apex 8-8.5 mm wide. Leaves narrowly lanceolate, 16 by 2.5 cm, coriaceous, keeled below, base conduplicate, undulate, apex bidentate. Inflorescences arising in succession from the apex of the pseudobulb, fasciculate, 1-flowered; peduncle 0.8 cm long, peduncle-scales few. Floral bract triangular, very short. Pedicel 2.5 cm long; ovary 0.4 cm long, 6-grooved, together with the pedicel slightly sigmoid. Flower resupinated, 3.7 cm wide. Dorsal sepal strongly recurved, elliptic-oblong, 2 cm by 8.5 mm, strongly convex, apex narrowly obtuse. Lateral sepals obliquely oblong, 2.15 cm by 8 mm in the middle, at the base 9.3 mm wide, apex lightly recurved, subacute; mentum oblongoid, 0.73 cm long, curved, obtuse. Petals recurved, widely patent, obliquely ovate, shortly convexly clawed at the base, 2.25 cm by 12 mm, apex broadly obtuse, apiculate. Lip 3-lobed below the middle, at one third above the base recurved, 1.55 by 0.97 cm, elastically attached to the column-foot, with two papillose basal keels diverging towards the apex, extending to the base of the midlobe, in the basal 2/3 of the midlobe with an oblong hairy cushion-like callus, transversely rugulose on either side of the callus; lateral lobes erect, falcate-triangular, concave, subacute; midlobe narrowly oblong, constricted near the middle, 0.8 by 0.48 cm, slightly widened in upper part, margins recurved, apex subtruncate. Column obliquely conical, 0.4 cm long, clinandrium 3-lobulate, the lobules triangular, the laterals weakly denticulate, stigma 5-angled-elliptic; column-foot at an acute angle with the ovary, 0.7 cm long, strongly incurved, obtuse. Anther transversely cucullate, in front obtuse, glabrous. Pollinia oblong, 1 mm long.
(after Smith, 1911).

Colours:

Flower orange-yellow, the keels on the lip pale yellow with red spots, with confluent red spots between the keels, lateral lobes lemon-yellow.

Habitat:

Epiphyte in lowland and montane forest, altitude 250 to 2300 m.

Distribution:

New Guinea (endemic).

Distribution New Guinea:

Papua (Nabire, Puncak Jaya, Merauke, and Jayapura Regencies); Papua New Guinea (Sandaun, Madang, and Morobe Provinces).

Map: Dendrobium auricolor J.J.Sm., distribution map, redrawn after N.H.S. Howcroft, Orchadian 7 (1981) 7.

Cultivation:

Intermediate growing epiphyte.

Flowering time in the wild:

May, June, September to December.

Literature:

Smith, J.J. 1935. Nova Guinea 18, 1: 42.
Howcroft, N.H.S. 1981. Orchadian 7: 6, fig.
O'Byrne, P. 1994. Lowland Orchids of Papua New Guinea: 216, fig., pl.

Notes:

Diplocaulobium auricolor belongs to a trio of very showy species, all characterised by the broad petals, but each quite distinct in the shape of the lip. The other members are Diplocaulobium regale and Diplocaulobium centrale.