注：名称已修订，正名是：无柱兰 Ponerorchis gracilis

Amitostigma gracile (Blume) Schlechter, Repert. Spec. Nov. Regni Veg. Beih. 4: 93. 1919.无柱兰 wu zhu lan

Mitostigma gracile Blume, Mus. Bot. 2: 190. 1856; Amitostigma chinense (Rolfe) Schlechter; A. formosensis (S. S. Ying) S. S. Ying; A. yunkianum Fukuyama; Cynosorchis chinensis Rolfe; C. gracilis (Blume) Kraenzlin; Gymnadenia gracilis (Blume) Miquel; G. tryphiiformis H. G. Reichenbach; Orchis formosensis S. S. Ying; O. gracilis (Blume) Soó; O. gracilis var. chinensis(Rolfe) Soó; O. sooi S. S. Ying; O. yunkiana (Fukuyama) S. S. Ying; Ponerorchis formosensis (S. S. Ying) S. S. Ying.

Plants 7-25 cm tall. Tubers ovoid to oblong-ellipsoid, 8-15 × 5-10 cm. Stem with 1 or 2 tubular sheaths at base, 1-leaved. Leaf usually basal, porrect, oblong to ovate-lanceolate, 3-12 × 0.8-3 cm, apex obtuse or acute. Peduncle with 1 sterile bract; rachis 0.5-4 cm, subdensely 5- to more than 15-flowered; floral bracts ovate-lanceolate, 2-3 mm, much shorter than ovary. Flowers often secund, pink, purplish red, or purple; ovary and pedicel 4-8 mm, usually straight. Dorsal sepal ovate, concave, 2-3 × 1.2-2 mm, 1-veined, apex obtuse; lateral sepals erect to spreading, ovate to obovate, slightly oblique, 2-3 × 1.2-1.8 mm, 1-veined, apex obtuse. Petals connivent with dorsal sepal and forming a hood, elliptic to ovate, oblique, 2-3 × ca. 2 mm, 1-veined, apex acute to obtuse; lip obovate, 3.5-5(-7) × 2.5-3.2 mm, 5-7(-9)-veined, base cuneate, 3-lobed above middle; lateral lobes linear-oblong to triangular, often falcate, 1-2 × 0.5-0.8 mm, apex obtuse-truncate or acute; mid-lobe obovate, 2-2.8 × 1.2-1.8 mm, larger than lateral lobes, apex truncate or obtuse-rounded, sometimes emarginate; spur pendulous, straight to very slightly incurved, cylindric, 1-2.5(-3.5) mm, much shorter than ovary, apex obtuse; viscidia elliptic; stigma lobes subclavate. Fl. Jun-Jul, fr. Sep-Oct. 2n = 42.

Damp rocky soils in forests, crevices, valleys; 200-3000 m. Anhui, N Fujian, Guangxi, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangsu, Liaoning, Shaanxi, Shandong, Sichuan