Description from Flora of China
Serapias helleborine Linnaeus subsp. longifolia Linnaeus, Sp. Pl. 2: 950. 1753; Cephalanthera acuminata Lindley; C. ensifolia (Swartz) Richard var. acuminata (Lindley) Tang & F. T. Wang; C. mairei Schlechter; C. thomsonii H. G. Reichenbach.
Plants leafy, autotrophic, 20-50 cm tall. Stem slender to somewhat robust, with 3-5 loosely clasping basal sheaths, 4-7-leaved. Leaves elliptic, lanceolate, or oblong-lanceolate, 4-16 × 0.5-3 cm, apex acuminate to long acuminate. Inflorescence subdensely 2-20-flowered; rachis 1.5-6 cm; floral bracts linear-lanceolate to narrowly triangular, basal 1 or 2 usually foliaceous and to ca. 70 mm, distal ones 2-6 mm. Flowers weakly spreading, white, 1-1.5 cm; pedicel and ovary 6-10 mm. Sepals narrowly rhombic-elliptic or narrowly elliptic-lanceolate, 11-16 × 3.5-4.5 mm, 5-veined, apex acuminate or subacute. Petals subobovate, 7-8 × ca. 4 mm, 5-7-veined, apex acute or mucronate; lip 5-7 × 6-9 mm, 2-partite; hypochile saccate, enclosed within bases of lateral sepals, with a small orange patch in middle of disk; hypochile lobes erect and embracing column, subovate-triangular, 3-4 mm, apex subacute; epichile triangular-cordate, 3-4 × 5-6 mm, with 3-5 orange lamellae, densely papillose toward apex, apex obtuse to acute. Column 4-6 mm, with 2 small oblong wings; anther 2-2.5 mm; stigma stalked. Capsule elliptic, 1.7-2 × 0.6-0.8 cm. Fl. May-Jun, fr. Sep-Oct. 2n = 16, 32, 34, 34 + 2B, 42.
The extensive extra-Chinese synonymy is not cited here.
Forests, thickets, along streams, open grasslands; 1000-3600 m. S Gansu, W Henan, W Hubei, S Shaanxi, S Shanxi, W Sichuan, S and SE Xizang, NW Yunnan [Bhutan, India, Kashmir, Myanmar, Nepal, Pakistan; N Africa, SW Asia, Europe].