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).
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).
Colours: Sepals and petals yellow-green, outside tinged brownish; lip white.
Habitat: Epiphytic or often terrestrial in open montane forest and grassland. Altitude 1100 to 2550 m.
Flowering time in the wild: Throughout the year.
Distribution: New Guinea, Bismarck Archipelago, Solomon Islands.
Distribution in 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).
Notes: This is a widespread species, often growing as a terrestrial in open places in the mountains.
Cultivation: Intermediate growing terrestrial, prefers light position.
Dendrobium prostheciglossum Schltr. var. obtusilobum Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 556; 21 (1923) t. 187, fig. 701.
Type: Schlechter 18805 (holo B, lost; iso AMES, E, G, K, L, NSW).
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 yellowish green, outside tinged brownish; lip white.
Habitat: Epiphyte on tree trunks in montane forest. Also terrestrial on steep slopes. Altitude 2000 to 2400 m.
Flowering time in the wild: February, November.
Distribution: New Guinea (endemic).
Distribution in New Guinea: Papua (Manokwari and Jaya Wijaya Regencies); Papua New Guinea (Eastern Highlands Province).
Cultivation: Cool growing epiphyte or terrestrial.