Orchids of New Guinea

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Dendrobium capituliflorum

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

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

Synonyms:

Pedilonum capituliflorum (Rolfe) Brieger, in Schltr., Orchideen, ed. 3, I/A (1981) 679, t. 681 (capitatium; capituliferum)); .
Dendrobium capituliflorum Rolfe var. viride J.J.Sm., Nova Guinea 14 (1929) 433.
- Type: Feuilleteau de Bruyn 163 (lecto: BO; isolecto L, chosen by Dauncey); Gjellerup s.n, Humbolt Bay (syn BO); Janowsky [Kornasi] s.n. (syn: BO!); Thomsen s.n. (Syntype: BO (photo); Bogor cult. (Branderhorst) 50 bBogor cult.243 (Lam) (syn BO)
Dendrobium confusum J.J.Sm., Bull. Dép. Agric. Indes Néerl. 45 (1911) 5; Nova Guinea 8, 3 (1911) 570, t. 94B.
- Type: Bogor cult. (Branderhorst) 50 b ( syn: BO, L); Bogor cult. (Branderhorst) 54 (syn: BO).
Dendrobium constrictum auct. non J. J. Sm.: Smith (1909) 79 p.p., t. XXVII, 87 f. a).
Dendrobium ophioglossum auct. non Rchb. f.: White (194 3a: 18-19 f.)
Dendrobium purpureum auct. non Roxb.: Hunt (1971: 178)
Pedilonum purpureum auct. non (Roxb.) Brieger: Brieger (1981: f. 491, 1).

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 white or 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.

Distribution:

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

Distribution 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).

Cultivation:

Warm growing epiphyte.

Flowering time in the wild:

Throughout the year. Flowers last 1 to 3 months.

Classification:

Family Orchidaceae
Subfamily Epidendroideae
Tribe Dendrobieae
Subtribe Dendrobiinae
Genus Dendrobium
Section Calyptrochilus
Species Dendrobium capituliflorum

Literature:

O'Byrne, P. 1994. Lowland Orchids of Papua New Guinea: 288, fig., pl..
Lewis, B. & P.J. Cribb. 1991. Orchids of the Solomon Islands and Bougainville: 192, pl. 10E.
Schlechter, R. 1912. Repert. Spec. Nov. Regni Veg. Beih. 1: 506
Schlechter, R. 1923. Repert. Spec. Nov. Regni Veg. Beih. 21: t. 171, fig. 639.
Smith, J.J. 1913. Nova Guinea 12, 1: 56.

Notes:

Dendrobium capituliflorum Rolfe is a common lowland species. The usually abundantly produced inflorescences with white and greenish flowers are very dense, almost head-like. It may be distinguished from the habitually quite similar Dendrobium constrictum J.J.Sm. by the petals and lip which are quite flat and narrowly oblong, elliptic to obovate-oblong, acute to acuminate, with minutely erose-serrulate margins (versus lip and petals concave, elliptic, ovate-, oblong-, or obovate-elliptic, with obtuse or obtusely-rounded tip and erose-ciliate or erose-fimbriate margins).