Iris chinensis Bunge (1833), not Curtis (1797); I. rosthornii Diels.

Rhizomes creeping, thick. Roots slender. Leaves mainly in basal fans, yellowish green, broadly sword-shaped, curved, 15--50 × 1.5--3.5 cm, base surrounded by fibers. Flowering stems 1- or 2-branched, 20--40 cm, 1- or 2-leaved; spathes 2 or 3, green, lanceolate, 3.5--7.5 × 2--2.5 cm, 1- or 2-flowered, apex acuminate. Flowers bluish violet, ca. 10 cm in diam.; pedicel to 1 cm. Perianth tube slender, to 3 cm; outer segments mottled darker around conspicuous, white, irregularly toothed crest, broadly ovate, 5--7 × ca. 4 cm, apex retuse; inner segments spreading horizontally at anthesis, elliptic, 4.5--5 × ca. 3 cm. Stamens ca. 2.5 cm; anthers bright yellow. Ovary cylindric, 1.8--2 cm. Style branches pale bluish violet, ca. 3.5 cm. Capsule ellipsoid or obovoid, 4.5--6 × 2--2.5 cm. Seeds black-brown, pyriform, with very small aril. Fl. Apr--May, fr. Jun--Aug. 2 n = 24, 28, 32.

White-flowered plants have been recognized as Iris tectorum f. alba (Dykes) Makino (Ill. Fl. Nipp. 714. 1940, based on I. tectorum var. alba Dykes, Gen. Iris, 103. 1913). The native distribution and ecology of I. tectorum are uncertain because the species is very widely cultivated and naturalized in China. It is also cultivated in Bhutan (where it has become naturalized), and India.

Forest margins, sunny banks, meadows, damp places, beside water; 500--3500 m. Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Jiangsu, Jiangxi, Qinghai, Shaanxi, Shanxi, Sichuan, Xizang, Yunnan, Zhejiang [Japan, Korea, ?Myanmar].