Orchids of New Guinea

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Dendrobium aurantiroseum

Dendrobium aurantiroseum P.Royen ex T.M.Reeve, Orchadian 7 (1982) 130, fig. 2.

Type: Balgooy, van 887 (holo LAE; iso CANB, K, L).

A creeping epiphytic herb, often embedded in loose moss and very straggly (more compact if exposed to direct sunlight). Roots smooth, slender, 1-1.5 mm diameter. Rhizomes distinct, usually short, c. 2 mm diameter. Pseudobulbs ovoid to fusiform, with 3-6 nodes, becoming rugose with age, 0.5-12 by 0.2-1.6 cm, 1- or 2-leaved. Leaves subpetiolate, elliptic-lanceolate (sometimes linear-lanceolate), 2-28 by 0.9-3.8 cm, acute, glabrous. Inflorescences arising from any of the nodes on defoliated stems, many-flowered in dense to subdense racemes; peduncle 2-20 mm long, rachis 4-15 mm long. Bracts ovate, 5-10 by 2.5-5 mm, acuminate. Ovary with pedicel curved, glabrous, 1.7-2.2 cm long. Flowers 1.8-2.8 cm long, fleshy, glabrous, not widely opening. Dorsal sepal oblong-ovate, 0.9-1.5 cm by 3.5-5 mm, obtuse to subacute. Lateral sepals 1.8-2.6 cm by 5-8 mm, obtuse. Petals obovate-spathulate, 0.9-1.5 cm by 4-5 mm, obtuse. Lip simple, obovate-spathulate, 17-22 by 6-8 mm (expanded), constricted below centre with distinct U-shaped cross-ridge, basal section saccate, side margins incurved, apex subacute. Column typical of section, 3.5-4 by 3-3.5 mm; column foot 9-13 mm long; anther c. 1.5-2 by 1.5 mm; pollinia c. 1.5 mm long.
(after Reeve, 1982).

Colours:

Pseudobulbs green to brown. Leaves green sometimes suffused with purple underneath. Flower pink to mauve with white apices and prominent orange to orange-red band on the upper part of the lip (apex white). Anther and pollinia greyish-maroon.

Habitat:

Epiphytes on tree trunks, growing in moss cushions, usually in rather deep shade. Altitude 2100 to 3350 m.

Distribution:

New Guinea (endemic).

Distribution New Guinea:

Papua (Jaya Wijaya Regency); Papua New Guinea (Southern Highlands, Enga, Madang, Western Highlands, Simbu, Eastern Highlands, Central, and Oro Provinces).

Map: Dendrobium aurantiroseum P.Royen ex T.M.Reeve, distribution map.

Cultivation:

Cool growing epiphyte, requires a shaded and humid position.

Flowering time in the wild:

Throughout the year. Flowers last two or three months.

Classification:

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

Notes:

Dendrobium aurantiroseum is a common species in the moss forests of Papua New Guinea. It may be recognised by the fusiform pseudobulbs that carry only one or two acute leaves.