Orchids of New Guinea

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Dendrobium alaticaulinum

Dendrobium alaticaulinum P.Royen, Alp. Fl. New Guinea 2 (1979) 328, fig. 113.

Type: NGF (Vandenberg) 39665 (holo CANB; iso BRI, L, LAE).

Stems usually pendulous, flexuose, more or less fleshy, usually branching, 3-28 by 0.07-0.25(-0 .35) cm, 5- or 6-winged when dried, glabrous; internodes 0.25-0.8 cm long, slightly trapezoid. Leaves thin, usually all twisting in one plane, ovate-lanceolate, (0.45-)0.8-1.8(-2.4) by (0.15-)0.2-0.35(-0.5) cm, subcaudate-acuminate by the extended midrib, midrib slightly grooved above, crested below, lateral nerves numerous, prominent on either side, margins thin, irregularly coarsely scarious-papillate along entire length but more wavy in lower- and more papillate in apical part, underside of midrib coarsely papillate mainly in apical part and wavy to about halfway; sheaths equalling or slightly longer than the internodes, 3-5 mm long, ribbed, glabrous. Inflorescence solitary, 1.2-1.8 cm long, densely 3-10-flowered; peduncle 0.1-0.5 cm long; rachis flexuose, stout, 0.3-0.6 by 0.05-0.1 cm. Bracts ovate, boat shaped, 25 by 1-2.5 mm, caudate, slightly clasping the rachis, 5-nerved, glabrous. shallowly concave, ovate to triangular; apex tapering strongly to acute, caudate; margin coarsely erose , 3- 5-nerved, glabrous. Pedicels glabrous, 5-6 mm long, 5-ribbed. Ovary glabrous, claviform, 3-4 by 1 mm, slightly curved, 5-ribbed, slightly bullate along median rib. Median sepal glabrous, oblong-elliptic, 5-6 by 1.5-2 mm, shortly subulate-acute, 3-nerved, the nerves somewhat prominent on outside in basal part. Lateral sepals glabrous, ovate, the lower 4-5 mm forming a stout 4-5 mm long, rounded, spur-like mentum, margins in lowest 2.5-3 mm connate to each other, apical part slightly spreading, ovate, 5-7 by 3-3.5 mm, subulate-acute, 4-nerved, midrib slightly crested. Petals oblong-obovate, 4.5-5 by 1.5 mm, acute or acutish, 1-nerved, margin in upper half serrate-papillate. Lip glabrous, 5-nerved, spathulate in outline, 10-11 by 3 mm, obovate in apical half, margins slightly folded inwards, stronger so towards basal half of lip, scarious, papillate in upper half, narrowing into a retrorse, glabrous, transverse septum, claw oblong, boat-shaped. Column stout and short, 3 by 1.5 by 1.5 mm. Stelidia indistinct, scarious. Anther cucullate, 1.5 by 1.5 by 1 mm, truncate and fimbriate at tip, retuse and 2-humped at base. Column-foot 5 mm long, ventricose in frontal part.
(after van Royen, 1979).

Colours:

Flowers orange or pink at the base, white or pinkish in upper part.

Habitat:

Epiphyte in moss forest. Altitude (1500) 2200 to 3170 m.

Distribution:

New Guinea (endemic).

Distribution New Guinea:

Papua New Guinea (Enga, Southern and Eastern Highlands, Simbu, Madang, and Milne Bay Provinces).

Cultivation:

Cool growing epiphyte, keep in shade.

Flowering time in the wild:

February-September.

Classification:

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

Notes:

Dendrobium alaticaulinum P.Royen is a common species of sect. Calyprtrochilus Schltr in upland Papua New Guinea. It is closely related to Dendrobium caliculimentum R.S.Rogers, from which it differs mainly in the smaller size of all parts. Compact specimens may be confused with Dendrobium dichaeoides Schltr., but in that species the leaves are not articulated with the sheaths, as a result of which the dead leaves remain attached to the stems, and Dendrobium limpidum Schuit. & de Vogel in which the leaves are articulate with the stem but the stems are more compact and much shorter, and the flowers are uniformly coloured bright violet.