Bulbophyllum orbiculare J.J.Sm., Bull. Jard. Bot. Buitenzorg, sér. 2, 3 (1912) 75
Type: Gjellerup 483 (not BO, not L)
Rhizome creeping, 0.8-2.5 mm diam.; all rhizome scales distinctly shorter to slightly longer than the internodes. Roots in tufts below each pseudobulb. Pseudobulbs ovoid to approx. 0.6-7 cm apart, 0.5-2 by 0.4-1.5 cm, not flattened. Petiole 3-30 mm. Leaf blade elliptic to approx. obovate, 2-12 by 0.3-1.4 cm, index 1.5-33, tip obtuse to acute. Inflorescence 3-32 cm, up to 30-flowered. Peduncle 2.5-22 cm, glabrous to coarsely verrucose; bracts 4-6, the longest 3-7 mm. Rachis erect to arching, up to 11 cm. Floral bracts ovate to elliptic, 2.5-9 mm, tip acute to acuminate. Pedicel and ovary 4.5-10 mm, with the node 1-3 mm from the floral bract; glabrous to verrucose. Flowers 1 to many open at the time, moderately to widely opening. Median sepal ovate to elliptic, 3-7.5 by 3-5 mm, index 0.9-1.8, tip emarginate to acute, or apiculate, margins glabrous or finely papillose towards the tip; rather thin; surface glabrous. Lateral sepals oblique, 3.8-8 by 1.5-3 mm, index 2-3.7, tip obtuse to acute, or apiculate; otherwise as the median sepal. Petals oblique, elliptic to obovate, 1.2-3 by 0.7-2.2 mm, index 1-1.6, tip emarginate to acuminate; margins glabrous, erose or finely papillose; thin; surface glabrous. Lip approx. straight to distinctly curved, general outline (ob)ovate to elliptic, sometimes very slightly ovate, 1.5-3.5 by 0.8-1.8 mm, index 1.2-3.4 (not spread), tip rounded to subacute; margins generally ciliate, sometimes glabrous or papillose; thick; surface approx. glabrous or somewhat papillose locally; adx. concave towards the base, with a distinct median ridge, with 2 more distinct ridges converging in front but fused into a median ridge or only so near the top of the lip; abx. with a distinct, retuse median ridge. Column from ovary to the tip of the stelidia 0.9-1.8 mm; stigma protruding and generally with a distinct tooth at its base, approx. orbicular; column-foot without accessories. Stelidia inconspicuous, triangular, tip obtuse to acute; upper margin often erose or denticulate, with or without an inconspicuous, deltoid, rounded, to acute tooth along the lower margin. Anther abx. with a ridge towards its base; front margin somewhat protruding. Pollinia 2. (After Vermeulen, 1993)
Colours: Flower greenish suffused with dull purple.
Habitat: Epiphyte in lower montane forest; 0-2900 m.
Flowering time in the wild: January, February, March, May, June, July, August, September, October, November, December.
Distribution: Malesia (New Guinea), Solomon Islands.
Distribution in New Guinea: Papua (Indonesia); Papua New Guinea; see map 96-1304M.jpg.
Cultivation: Intermediate growing epiphyte.