Orchids of New Guinea

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Dendrobium lacteum

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).

Synonyms:

Euphlebium lacteum (Kraenzl.) Rauschert, Feddes Repert. 94 (1983) 447.
Dendrobium coxii F.M.Bailey, Queensland Agric. J. 16 (1906) 411.
- Type: Baxter Cox cult. s.n. (British New Guinea).
Dendrobium inaequale Rolfe ex Hook.f., Bot. Mag. 126 (1900) t. 7745.
- Type: [ Sander cult. s.n. (III-1899) (holo K).
Euphlebium inaequale (Rolfe) Rauschert, Feddes Repert. 94 (1983) 447.
Dendrobium purissimum Kraenzl., in Engl., Pflanzenr. IV. 50. II. B. 21 (1910) 264.
- Type: Beccari s.n. (Aru Isl., Grabu Lengan).
Dendrobium quinarium Rolfe, Bull. Misc. Inform. Kew (1901) 147.
- Type: Low cult. s.n. (VII-1898) (holo K).

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.

Distribution:

Aru Islands, New Guinea, Bismarck Archipelago.

Distribution New Guinea:

Papua (Jayapura Regency); Papua New Guinea (Gulf, Madang, Morobe, and Central Provinces; New Ireland).

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.

Flowering time in the wild:

Probably throughout the year. Flowers last only a few hours (fide O'Byrne).

Classification:

Family Orchidaceae
Subfamily Epidendroideae
Tribe Dendrobieae
Subtribe Dendrobiinae
Genus Dendrobium
Section Fugacia
Species Dendrobium lacteum

Literature:

Kraenzlin, F. 1910. Orchidaceae-Monandrae-Dendrobiinae I. In A. Engler, Das Pflanzenreich IV.50.II.B.21: 262.
O'Byrne, P. 1994. Lowland Orchids of Papua New Guinea: 284, fig., pl.
Schlechter, R. 1912. Repert. Spec. Nov. Regni Veg. Beih. 1: 479.
Schlechter, R. 1912. Repert. Spec. Nov. Regni Veg. Beih. 1: 478.
Schlechter, R. 1923. Repert. Spec. Nov. Regni Veg. Beih. 21: t. 162, fig. 606.

Notes:

Dendrobium lacteum Kraenzl. is similar to Dendrobium coeloglossum Schltr., 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.