Orchids of New Guinea

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Dendrobium archipelagense

Dendrobium archipelagense Howcroft & Takeuchi, Sida 20 (2002) 464, fig 3, 4.

Type: W Takeuchi & J Wiakabu 9979 (holo LAE; iso A) (fl. in spirit).

Tufted epiphyte. Rhizomes short. Pseudobulbs at the base swollen, in the lower part fusiform, distally more slender, subcylindrical, to 50 by1-2 cm; nodal sheaths persistent, shorter than the internodes. Leaves distichous, lanceolate-ovate, thick, coriaceous, 7.5- 9.5 by 2.0-3.0 cm; adaxially slightly concave, abaxially convex; apex asymmetrically emarginate. Inflorescences one or several per pseudobulb, racemose, erect, inserted at the apex or slightly lower; peduncle to 9 cm long, peduncular and floral bracts tubular; rachis to 40 by 0.2-0.3 cm. Pedicel glabrous, c. 2.2 cm long; ovary glabrous, c. 0.9 cm long. Flowers 5-10 per raceme, usually wide-opening, 4.0- 5.5 by 3.5 cm. Median sepal recurved, twisted through one turn, oblong-lanceolate, 2-2.6 by 0.6- 0.7 cm; apex acuminate. Lateral sepals recurved, oblong-lanceolate, 2.5-3.3 by 0.9 cm at the base; apex acute or acuminate. Mentum narrowly conical, 0.9-1cm long; apex straight or slightly decurved. Petals twisted through one or two turns, spreading, linear, 3-4.5 by 0.25-0.4 cm; apex acute. Lip porrect, 3-lobed, 2-2.3 by 1-1.5 cm; lateral lobes oblong-elliptic,1.15 by 1.5 cm, overlapping the base of the midlobe; midlobe not recurved, ovate, c.1 by 1 cm, with acute to apiculate apex; 5-keeled, keels slightly raised, not lamellate or crested, the lateral ones not extending past the base of the midlobe, the median one extending to the apex of the midlobe, with rounded apex. Column 0.5 cm long; foot at 10° to column; apex laterally bilobed. Fruit with persistent perianth.
(After Howcroft & Takeuchi, 2002)

Colours:

Leaves green to yellow-green.Flowers pale green turning to yellow-green with age. Lip with some purple veins. the keels are usually bordered with violet and often has violet reticulations up to the median, and sometimes the distal portion of the midlobe.

Habitat:

Lowland rainforest, common on coastal trees. Altitude 0-250 m.

Distribution:

Malesia (New Guinea).

Distribution New Guinea:

Papua New Guinea (West and East New Britain and New Ireland Prov.), see map.

Cultivation:

Warm growing epiphyte. Tolerates exposed position.

Flowering time in the wild:

January, in cultivation April to October.

Classification:

Family Orchidaceae
Subfamily Epidendroideae
Tribe Dendrobieae
Subtribe Dendrobiinae
Genus Dendrobium
Section Spatulata
Species Dendrobium archipelagense

Notes:

Dendrobium archipelagense is similar to Dendrobium antennatum in the size of the lip, but differs in the lateral lobes which are 70-80% of the labellum length against in D. antennatum 55- 70%, and the relatively longer petals.

D.archipelagense differs from D.strepsiceros in the shorter lip with relatively shorter median lobes and the lateral lobes are 70-80% of the lip length against 50-58% in D.strepsiceros, while the median keel is not raised as a triangular lamella like in the latter.