Description from Flora of China
Arethusa plicata Andrews, Bot. Repos. 5: 321. 1803; Aplostellis velutina (E. C. Parish & H. G. Reichenbach) Ridley; Cordyla discolor Blume; Nervilia biflora (Wight) Schlechter; N. dallachyana (F. Mueller ex Bentham) Schlechter; N. discolor (Blume) Schlechter; N. discolor var. purpurea (Hayata) S. S. Ying; N. plicata var. purpurea (Hayata) S. S. Ying; N. purpurea (Hayata) Schlechter; N. velutina (E. C. Parish & H. G. Reichenbach) Schlechter; Pogonia biflora Wight; P. discolor (Blume) Blume; P. dallachyana F. Mueller ex Bentham; P. plicata (Andrews) Lindley; P. pudica Ames; P. pulchella J. D. Hooker; P. purpurea Hayata; P. velutina E. C. Parish & H. G. Reichenbach; Roptrostemon discolor (Blume) Blume.
Tuber whitish, globose to ellipsoid, 5-20 mm in diam. Leaf abaxially green or dark purple, adaxially pale to dark green and sometimes with purple or yellowish blotches, orbicular-cordate, 7.5-11 × 10-13 cm, plicate, pubescent primarily on veins, many veined, base cordate, apex acute; petiole-like stalk erect, purple or dark green, 1.5-3 cm. Inflorescence 12-20 cm, 2-flowered; peduncle dark green or purple, with 2 or 3 tubular sheaths; floral bracts lanceolate, 5-7 × 1-2 mm, apex acuminate. Flowers nodding, resupinate, usually opening widely; pedicel and ovary 10-14 mm, ridged. Sepals brownish yellow or purple with purplish red venation, spatulate, 15-25 × 2.5-4 mm, apex acute. Petals brownish yellow or purple with purplish red venation, linear-oblanceolate, 14-22 × 2.5-3 mm, apex acute; lip brownish tinged yellow at center and with purplish brown venation, or pale purple tinged dark purple at center and with purplish red venation, rhombic to ovate, 13-20 × 10-13 mm, spurless, obscurely 3-lobed above middle; lateral lobes erect and loosely enclosing column, small, rounded; mid-lobe subsquare or ovate, longitudinally folded at apex, apex truncate-obtuse when flattened or sometimes slightly emarginate; disk glabrous, with a ridge running from near base almost to apex of mid-lobe. Column white, 7-10 mm, apex dilated; stigma suborbicular. Fl. May-Jun. 2n = 20, 72, 108.
This is a variable species in terms of lip shape, ornamentation, and color, as well as leaf size and color, and several forms have been recognized as distinct species by some authors. Further examination of this complex is required.
Forests, shaded and damp places along valleys; 200-1000 m. Fujian, S Gansu, Guangdong, Guangxi, Sichuan, S Taiwan, Yunnan [Bangladesh, Bhutan, India, Indonesia, Laos, Malaysia, Myanmar, New Guinea, Philippines, Thailand, Vietnam; N Australia].