Orchids of New Guinea

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Dendrobium leucocyanum

Dendrobium leucocyanum T.M.Reeve, Orchadian 7 (1982) 134, fig. 4.

Type: Reeve 308 (holo LAE; iso AMES, BISH, BO, CBG, E, K, L, NSW, UPNG, herb Renz).

A creeping, mat-forming, epiphytic herb, up to 5 cm high. Roots smooth, slender, 0.3-1 mm diameter. Rhizomes distinct, prostrate, 2-3 mm diameter. Pseudobulbs rather closely spaced, globose to clavate, 0.5-2 cm by 5-15 mm, soon becoming rugose, when young covered with scarious cataphylls, 2-, rarely 3-leaved at apex. Leaves ovate-elliptic to elliptic, 0.6-3.5 by 0.3-1.8 cm, subacute to acute, often mucronate. Inflorescences terminal, arising from the apices of defoliated pseudobulbs, densely packed with 5-25 flowers, peduncle and rachis very short; bracts ovate, acute to acuminate, 2-4 mm long. Ovary with pedicel 7-9 mm long. Flowers 8-11 mm long, glabrous but sometimes slightly verrucose on the outside. Dorsal sepal oblong, 3.5-4.5 by 2.0-2.5 mm, subacute. Lateral sepals 7.5-10 by 2.5-3 mm; mentum obtuse or bilobed at the apex. Petals obovate-spathulate, 3-4 by 1.5-2 mm, acute. Lip simple, oblong-spathulate, 7-9 by 2.5-3 mm (expanded), divided into 3 sections when viewed from the side - the top section is separated by a distinct cross-ridge whilst the lower sections may be slightly constricted at the junction; apex subacute and slightly reflexed. Column c. 1.5 by 1.5 mm; column foot 5-6 mm long; anther c. 1 by 1 mm; pollinia c. 0.6 mm long.
(after Reeve, 1982).

Colours:

Pseudobulbs reddish brown. Leaves pale glaucous green to mid green, often purplish below. Sepals and petals tepals pale bluish green, sometimes tinged violet, with apices grass green, lip whitish with green apex. Ovary tinged pale indigo-blue. Column whitish. Anther whitish tinged blue-violet. Pollinia green.

Habitat:

Epiphyte on tree trunks in montane forest, not particularly host specific, recorded on Nothofagus, Dacrycarpus and Ficus dammaropsis. Altitude 1600-2600 m.

Distribution:

New Guinea (endemic).

Distribution New Guinea:

Papua (Paniai and Jaya Wijaya Regencies); Papua New Guinea (Enga, Eastern Highlands, Madang, and Morobe Provinces).

Map: Dendrobium leucocyanum T.M.Reeve, distribution map.

Cultivation:

Cool growing epiphyte. Requires light shade and perfect drainage.

Flowering time in the wild:

March to December. Flowers last about two months.

Notes:

Dendrobium leucocyanum is a very distinctive member of section Pedilonum, both by its mat-forming habit (similar to, but coarser than Dendrobium parvulum) and its peculiar bluish green flowers produced in very dense, almost spherical racemes from the apices of the bare, reddish brown, wrinkled pseudobulbs.