Dendrobium margaretiae

Dendrobium margaretiae T.M.Reeve, Orchadian 7 (1983) 205, fig. 3 ('margaretae').

Type: Reeve 707 (holo LAE; iso AMES, BISH, BO, CBG, E, K, L, NSW, UPNG).

Small creeping epiphytic herb up to 3 cm high, often forming large mats on tree trunks. Roots glabrous, 0.5-1 mm diameter. Rhizomes cylindrical, branched, with pseudobulbs 5-15 mm apart. Pseudobulbs obliquely ellipsoid to oblongoid, 3-7 (-9) by 3-5.5 mm, becoming rugose (c. 5-angled) with age, grooved on the lower side where appressed with rhizome, 1-leaved. Leaves shortly petiolate, erect to semi-erect, ovate to elliptic, 0.6-1.6 (-2.4) cm by 4-7 (-11) mm, subacute (sometimes apiculate), thick and fleshy. Inflorescences single flowered, with 2 successive inflorescences on each pseudobulb, arising from near the base of the leaf petiole; peduncle reasonably persistent, 3-4 mm long. Bracts minute. Ovary with pedicel curved, 7-11 mm long. Flowers 7-11 mm diameter, glabrous. Dorsal sepal broadly ovate, 3-4.5 by 3-4 mm, obtuse to subacute. Lateral sepals obliquely triangular-ovate, 6-8 by 4-4.5 mm, forming relatively large mentum 4-5 mm long. Petals small, 2.5-3 by 1-1.5 mm. Lip hinged, not curved in side view, attenuated at base with dilated apex slightly bilobed (sub-reniform), 6.5-7.5 by 4.5-5 mm. Column short c. 2 by 1.5 mm; column foot dished, c. 4 by 2 mm, anther c. 1 by 1 mm; pollinia c. 0.4 mm long. Fruit somewhat triangular in cross-section.
(after Reeve, 1983).

Colours: Roots white with green tips. Pseudobulbs greenish to brown. Leaves mid to dark green sometimes tinged purplish. Flower yellow with greenish to maroon ovary and mentum, lip maroon with dark yellow apex. Column yellowish, foot maroon, anther yellowish, pollinia yellow.

Habitat: Epiphyte in montane forest, e.g. on Castanopsis acuminatissima, in moderate shade. Altitude 1500 to 2000 m, perhaps up to 2500 m.

Flowering time in the wild: April, July, December. Flowers lasting 10-18 days.

Distribution: New Guinea (endemic).

Distribution in New Guinea: Papua New Guinea (Southern Highlands, Enga, and Eastern Highlands Provinces).

Map: MARGAMAP.JPG [Dendrobium margaretiae T.M.Reeve, distribution map.]

Notes: Dendrobium margaretiae is quite similar to Dendrobium bulbophylloides but it is distinguished by the smaller pseudobulbs, the paired inflorescences (two per pseudobulb opening successively), the yellow colour of the smaller flowers and by the lip lacking a transverse callus.
(largely after Reeve, 1983).

Cultivation: Cool growing epiphyte, requiring moderate shade and perfect drainage.