Dendrobium lacteum Kraenzl., Österr. Bot. Zeitschr. 44 (1894) 334.
Type: Micholitz s.n. (1894) (New Ireland, between Cape Carteret and Port Praslin) (holo HBG, iso HBG).
Rhizome short, creeping, often unbranched. Stems crowded, slender at base, thickened in upper part, 4-angled, 12-50 cm long, usually 2-, rarely up to 5-leaved, with 5-13 internodes. Leaves linear to lanceolate-ovate, 5-12 by 1.7-3 cm, papyraceous, base shortly petiolate, apex acute to acuminate. Inflorescences 2-3 per stem, from nodes below the leaves, racemose, very short, 1-2-flowered, with some sterile bracts below the flowers. Floral bracts ovate, much shorter than the pedicel with ovary, apex acute, thin-textured. Pedicel with ovary 0.8-2.5 cm long. Flowers up to 5 cm across, ephemeral. Dorsal sepal ovate-lanceolate, 2.5-3.2 cm long, apex long acuminate. Lateral sepals narrowly obliquely ovate-triangular, falcate, 2.5-3 cm long, apex long acuminate; mentum 4-6 mm long. Petals a little narrower than the sepals, lanceolate, 2.5-3 cm long, apex acuminate. Lip clasping the column, transversely oblong when expanded, 1.2-1.5 by 1.9-2.2 cm, at the base with a fleshy callus with 3 short radiating lines in front which terminate in a hook-shaped lamella (or only the lateral lines terminate in such a lamella), in front of the lamellae pubescent, apex triangular-apiculate. Column c. 5 mm long, stelidia long, horn-like, filament very slender, short. Anther hairy in front.
(largely after Kraenzlin, 1910, and O'Byrne 1994).
Colours: Sepals and petals white, lip yellow inside, tinged purplish along the white margins, with 3-5 orange to red-brown or purple-brown lines, basal callus golden yellow with brown spots.
Habitat: Epiphyte in lowland and hill forest. Altitude 0-900 m.
Flowering time in the wild: Probably throughout the year. Flowers last only a few hours (fide O'Byrne).
Distribution: Aru Islands, New Guinea, Bismarck Archipelago.
Distribution in New Guinea: Papua (Jayapura Regency); Papua New Guinea (Gulf, Madang, Morobe, and Central Provinces; New Ireland).
Notes: Dendrobium lacteum is related to Dendrobium coeloglossum, from which it is distinguished by the narrower sepals and by the lip having at most 3 hook-like lamellae, not five raised keels as in the latter.
Cultivation: Warm growing epiphyte. Requires shaded position and frequent waterings throughout the year. Difficult to keep, according to O'Byrne, as it is prone to rot.