Dendrobium capituliflorum

Dendrobium capituliflorum Rolfe, Bull. Misc. Inform. Kew (1901) 146.

Type: Sander cult. s.n. (III-1899) (holo K).

Roots from rhizome and base of stem, c. 1 mm diam, smooth, white-green. Rhizome very short, creeping. Pseudobulb erect, fusiform to club-shaped, 3- to 7-leaved, older stems bare, 4-45 cm long, nodes 6-30 mm apart; basal internodes swollen, internodes above base slender and cylindrical, 2-7 mm wide, broadening rapidly after 2-4 nodes; swollen central section 7-20 mm diam, then tapering gradually to apex. The grey-white sheaths persist for 2-3 years. Leaves suberect to spreading, ovate to lanceolate or oblong, 2.2-11.5 cm by 8-34 mm, thin, leathery, dark green with white veins or grey suffused purple or purple; tip acute to obtuse, unequally bilobed. Inflorescences 1-8 on bare stems, laterally from central or upper nodes, suberect, 2-4 cm long, with 15 to 80 tubular flowers in a densely crowded raceme. Peduncle short, 3-5 mm wide, green with 3-4 stiff brown sterile bracts at base. Floral bract ovate-triangular, 2-6 mm, green, acute. Pedicel and ovary 8-15 mm long, minutely hairy. Flower 1.2-1.8 cm long, not widely opening. Sepals and petals abaxially ridged, acute, apiculate, sepals minutely hairy abaxially. Dorsal sepal porrect, ovate-lanceolate, c. 0.7 cm by 2 mm, concave. Lateral sepals not wide-spreading c. 1.5 cm by 3.5 mm, concave; free part narrowly ovate; base oblong, extending to tip of mentum; mentum inflated, cylindrical, 8 mm long, parallel with the ovary. Lip porrect, c. 1.2 cm by 3.5 mm, obscurely 3-lobed, divided by lateral green transverse wall before 1/2 its length; lower section gutter shaped, slightly recurved, nectar-filled, with 2 low broad keels; front section gutter shaped, broadening and flattening towards apex; apex triangular, acute, margins erose to serrate. Column 2 mm long, apex denticulate above small stelidia; foot subparallel, c. 6 mm long, tapering to slender acute apex, with a central ridge. Pollinia 4 in 2 pairs, translucent olive-brown, often adhering to sticky irregular section of rostellum.
(after O'Byrne, 1994).

Colours: Flowers greenish white with grass green markings on the lip and anther.

Habitat: Epiphyte in lowland forests and plantations, including savannah and rainforest, occasionally lithophytic. Altitude 0 to 750 m, rarely up to 1800 m in montane forest.

Flowering time in the wild: Throughout the year. Flowers last 1 to 3 months.

Distribution: Moluccas, New Guinea, Solomon Islands, Carolines, Vanuatu, Fiji.

Distribution in New Guinea: Papua (Biak Numfor, Jayapura, and Merauke Regencies); Papua New Guinea (Gulf, East Sepik, Madang, Central, Oro, Milne Bay and West New Britain Provinces).

Notes: Dendrobium capituliflorum is a common lowland species of section Pedilonum. The usually abundantly produced inflorescences with greenish flowers are very dense, almost head-like. It may be confused with Dendrobium constrictum.

Cultivation: Warm growing epiphyte.