Orchids of New Guinea

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Dendrobium prostheciglossum

Dendrobium prostheciglossum Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 555; 21 (1923) t. 187, fig. 700.

Type: Schlechter 18174 (holo B, lost; iso AMES, BO, E, G, K, L, MO).Schlechter 18805 (holo B, lost; iso AMES, E, G, K, L, NSW).

Synonyms:

Trachyrhizum prostheciglossum (Schltr.) Brieger, in Schltr., Orchideen, ed. 3, I/A (1981) 687.
Dendrobium latifrons J.J.Sm., in L.S.Gibbs, Phytogeogr. Fl. Arfak Mountains. (1917) 118 (= var. obtusilobum).
- Type: Gibbs 5558 (holo BM).
?Dendrobium kryptocheilum Gilli, Ann. Naturhist. Mus. Wien 84, B (1980 publ. 1983) 26, fig. 14 (?= var. obtusilobum).
- Type: Gilli 369 (holo W)
Dendrobium villosipes J.J.Sm., Bull. Jard. Bot. Buitenzorg, sér. 2, 13 (1914) 64; Nova Guinea 12, 3 (1916) 328, t. 119, fig. 216.
- Type: Pulle 1097 (holo L).
Trachyrhizum villosipes (J.J.Sm.) Rauschert, Feddes Repert. 94 (1983) 469

Rhizome very short, roots elongated, filiform, densely verruculose, rough. Stems crowded, erect, slender, 30-90 cm by 1.2 mm, many-leaved except in the basal part, not branched. Leaf sheaths entirely covering the stem. Leaves erect-patent, lanceolate-oblong to oblong, 6-12 by 1.7-3 cm, apex subacute, strongly unequally bilobulate. Inflorescences racemose, erect-patent, 14 cm long, peduncle rather long, laxly 4-9-flowered. Floral bracts deltoid, very small, much shorter than the pedicel and ovary, apex obtuse. Pedicel and ovary 2.3 cm long, slender, glabrous. Flowers resupinated, c. 2 cm across. Dorsal sepal very broadly ovate, 1 cm long, apex obtuse, apiculate. Lateral sepals very broadly obliquely ovate, widened at the base, 1 cm long, apex obtuse, apiculate; mentum obliquely conical, 1 cm long, obtuse. Petals obliquely oblong, 0.9 cm long, margins minutely serrulate except in basal part, apex subacute. Lip 3-lobed in the middle, 1.5 by 1.6 cm, shortly clawed at the base, in basal half with a horseshoe-shaped callus which is somewhat spur-like extended at the base, the 'arms' decurrent on the base of the midlobe, midlobe with a low transverse 2-apiculate lamella, lateral lobes falcate-lanceolate, 0.7 cm long, subacute; midlobe broadly quadrate, 0.75 cm long, margin slightly undulate, apex truncate, bifid until the middle. Column short; column-foot 1 cm long, narrowed to the incurved apex.
(after Schlechter, 1912).

INFRASPECIFIC TAXA

Dendrobium prostheciglossum Schltr. var. obtusilobum Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 556; 21 (1923) t. 187, fig. 701.

Differs from Dendrobium prostheciglossum var. prostheciglossum in having broader leaves and broader, obtuse lateral lobes of the lip, which has a subcrenulate apex, a shorter basal claw, while the transverse lamella on the base of the midlobe is 4-dentate.

Colours:

Sepals and petals yellow-green, outside tinged brownish; lip white.
Sepals and petals yellowish green, outside tinged brownish; lip white.

Habitat:

Epiphytic or often terrestrial in open montane forest and grassland. Altitude 1100 to 2550 m.
Epiphyte on tree trunks in montane forest. Also terrestrial on steep slopes. Altitude 2000 to 2400 m.

Distribution:

New Guinea, Bismarck Archipelago, Solomon Islands.

Distribution New Guinea:

Papua (Manokwari, Paniai, Jaya Wijaya, and Jayapura Regencies); Papua New Guinea (East Sepik, Southern Highlands, Enga, Western Highlands, Madang, Morobe, and East New Britain Provinces).

Cultivation:

Intermediate growing terrestrial, prefers light position.
Cool growing epiphyte or terrestrial.

Flowering time in the wild:

Throughout the year.
February, November.

Literature:

Lewis, B. & P.J. Cribb. 1991. Orchids of the Solomon Islands and Bougainville: 209.

Notes:

This is a widespread species, often growing as a terrestrial in open places in the mountains.