Orchids of New Guinea

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Dendrobium laevifolium

Dendrobium laevifolium Stapf, Bot. Mag. 149 (1924) t. 9011.

Type: Colman cult. (Frost) s.n. (Louisiades, Rossel Isl.) (holo K) .

Synonyms:

Maccraithea laevifoliua (Stapf) M.A.Clem. & D.L.Jones, Orchadian 13 (2002) 497
Dendrobium occultum Ames, J. Arnold Arbor. 14 (1933) 108.
- Type: Kajewski 604 (holo Ames # 38084).
Pedilonum occultum (Ames) Rauschert, Feddes Repert. 94 (1983) 462

Tufted epiphyte, 2.5-18 cm high. Roots to c. 2 mm diameter. Rhizome short, to c. 0.5 cm. Pseudobulbs 0.7-4.5 by 0.2-l cm, to c. 6-noded, cylindrical, fusiform, flask-shaped or ovoid, crowded, apex 2-, occasionally 3-leaved (the third leaf then very small). Leaves (1.5-)5.5-14.5 by 0.5-2.5 cm, linear, oblong-lanceolate or elliptic, moderately thick, apex acute or subacute, mucronate, subpetiolate; sheaths tubular to c. 2 cm or more long, smooth, separating with age into loose spreading fibres. Inflorescences 1-2(-4)-flowered, mostly from leafless stems, terminal or from upper nodes, subsessile; bracts to 8 by 8 mm, rotundate to ovate-triangular, shortly acuminate or apiculate. Flowers 2-4.5 cm long, to 4.5 mm wide. Median sepal 12-25 by 5-11 mm elliptic-oblong to ovate-oblong, slightly keeled towards apiculate apex. Lateral sepals 20-30 by 5-l0 mm, oblong to ovate, gradually tapering towards acute or apiculate apex; basal fused part 4-7 mm long, tubular to narrow conical; mentum total length 8-20 mm, tip obtuse. Petals 12-19 by 6-11 mm obovate, rotundate or oblanceolate, apex obtuse apiculate. Lip to 21 by 3 mm c. 6 mm when expanded), oblanceolate, boat-shaped, papillose, margins upcurved, apex apiculate, with a crescent-shaped, shallow transverse callus c. 6 mm above the base. Column 4.5-5 by c. 2.5 mm foot 8-20 mm long, with a minute angular flap c. 2.5 mm from base; anther 1.5-2 mm wide; pollinia 1-1.5 mm long. Ovary obscurely triangular, angles rounded, shallowly 6-grooved; pedicel and ovary (8-)10-28 mm long. Fruit 28 by l0 mm, oblong-ovoid.
(after Reeve & Woods, 1989).

Colours:

Leaves green or deep green, sometimes suffused purple below and at margin and mid-nerve; sheaths mid-green. Flower colour variable, cream, cream suffused pink, red, reddish purple or purple-pink, lip similarly coloured or paler, sometimes orange, margin yellow, pink or orange, column pale green or pink.

Habitat:

Dendrobium laevifolium occurs in deep growths of lichen and moss on the trunks or slightly sloping branches of treelets a few feet above the mossy elfin forest bed almost constantly saturated with cold mist or light rain with brief bursts of very hot suns

Distribution:

Louisiade Archipelago, Bougainville, Solomon Islands, Santa Cruz Islands.

Distribution New Guinea:

Papua New Guinea (Louisiade Archipelago)

Map: Dendrobium laevifolium Stapf, distribution map, redrawn from T.M. Reeve & P.J.B. Woods, Notes Roy. Bot. Gard. Edinburgh 46 (1989) 286, map 8.

Cultivation:

Intermediate growing epiphyte, should be kept lightly shaded and moist at all times.

Flowering time in the wild:

March, August, October.

Literature:

Reeve, T.M. & P.J.B. Woods. 1990. Notes Roy. Bot. Edinburgh 46: 271, fig. 36, pl. 18A.
Lewis, B. & P.J. Cribb. 1991. Orchids of the Solomon Islands and Bougainville: 186, fig. 44 l-m, pl. 11C.

Notes:

Small plants of Dendrobium laevifolium could, at first glance, be mistaken for Dendrobium cuthbertsonii. The absence of warts on leaves and ovaries should ensure accurate identification.