Description from Flora of China
Aerides difformis Wallich ex Lindley, Gen. Sp. Orchid. Pl. 242. 1833; Ornithochilus delavayi Finet; O. eublepharon Hance; Sarcochilus difformis (Wallich ex Lindley) Tang & F. T. Wang.
Stems 2-4 cm, ca. 1 cm in diam. Leaves nearly basal, usually 2 or 3; leaf blade oblong-elliptic or obovate-elliptic, obovate, or oblong, falcate, 7-19 × ca. 5.5 cm, apex obtuse, acute, or acuminate; basal sheaths ca. 1 cm, embracing stem. Inflorescences laxly many flowered; branches spreading, to ca. 21 cm, base sheathed; sheaths overlapping, tubular, 3-6 mm; rachis 9-25 cm, glabrous; floral bracts pale brown, triangular, ca. 2 mm, acute. Flowers opening widely, 0.7-1 cm in diam.; sepals and petals yellow to green with several longitudinal red-brown striations, lip dark maroon with yellow markings at base and margin, spur maroon and green, column purplish brown; pedicel and ovary ca. 1 cm. Sepals and petals slightly recurved; dorsal sepal oblong, ca. 5 × 2 mm, obtuse; lateral sepals obliquely ovate-oblong, ca. as long as and wider than dorsal sepal, obtuse. Petals narrowly oblong, ca. 4 × 1.2 mm, entire or scabrous, obtuse; lip shortly clawed at base, 3-lobed; lateral lobes suberect, subovate; mid-lobe slightly incurved, anchor-shaped, clawed at base, 3-lobulate; lateral lobules large, margins fimbriate; apical lobule smaller, abaxially slightly beaked, margin entire and incurved, apex obtuse; disk with 1 purplish red, fleshy callus centrally, a pilose callus at front of and a callus on back of spur entrance; spur slightly curved, ca. 4 mm. Column ca. 2 mm, both front sides hairy. Fl. May-Jul. 2n = 38.
Ornithochilus difformis is represented in China by var. difformis; O. difformis var. kinabaluensis J. J. Wood, A. L. Lamb & Shim, from Borneo, is distinguished by having greenish yellow sepals and petals and a pure white lip with shorter fimbriate processes on the mid-lobe; more distinct, narrowly winglike lateral lobes; a smaller keel-like callus; and a shorter, usually less curved spur.
Epiphytic on tree trunks in open forests or at forest margins; 500-2100 m. S Guangdong, Guangxi, SW Sichuan, S and SW Yunnan [Bhutan, India, Indonesia, Laos, Malaysia, Myanmar, Nepal, Thailand, Vietnam].