Description from Flora of China
Diplochilus longifolius Lindley; Diplomeris boxallii Rolfe; Habenaria uniflora (Roxburgh) Griffith; Orchis uniflora Roxburgh; Paragnathis pulchella (D. Don) Sprengel.
Plants 7.5-22.5 cm tall. Tubers ellipsoid, ca. 10 × 5 mm. Leaves usually 2, basal, 1 larger than other, ensiform to linear-lanceolate, 3-10 × 0.5-1.8 cm, glabrous, base contracted into amplexicaul sheath, apex acuminate. Inflorescence erect, 6-18 cm, glabrous; floral bract broadly ovate, ca. as long as to slightly exceeding ovary, glabrous, apex acute. Flower usually solitary, erect, white, large; ovary and pedicel 10-12 mm, glabrous. Sepals spreading, oblong-lanceolate or ovate-lanceolate, 15-18 × ca. 6 mm, outer surface carinate, glabrous, apex acute or acuminate. Petals spreading, broadly obovate or ovate-oblong, 1.5-2.5 × 1-1.5 cm, apex acute; lip spreading, broadly obcordate, 1.8-2.8 × 1.5-2.2 cm, apex entire to shallowly emarginate and with a small acute tooth; spur pendulous, strongly incurved, cylindric, ca. 3.5 cm, slender, slightly thickened from middle toward apex, apex subacute to obtuse. Fl. Jul-Sep, fr. Oct.
Forests, grasslands; 600-2600 m. SW Guizhou, SW Sichuan, SE Xizang, NW Yunnan [NE India, Myanmar, Vietnam].