37. Iris japonica Thunberg, Trans. Linn. Soc. London, Bot. 2: 327. 1794.
蝴蝶花 hu die hua
Iris chinensis Curtis (1797), not Bunge (1833); I. fimbriata Ventenat.
Rhizomes dimorphic: suberect, thick; creeping, long, slender. Leaves basal, dark or yellowish green, glossy on 1 surface, dull on other, reddish purple at base, sword-shaped, 25--60 × 1.5--3 cm, midvein absent. Flowering stems erect, with 5--12 short, slender branches near apex; spathes 3--5, broadly lanceolate, 0.8--1.5 cm, 2--4-flowered, apex obtuse. Flowers pale bluish, 4.5--5.5 cm in diam.; pedicel 1.5--2.5 cm, stiff, persistent. Perianth tube 1.1--1.5 cm; outer segments obovate or elliptic, 2.5--3 × 1.4--2 cm, limb spreading, with blue blotching around central, yellow patch around prominent, yellow crest, margin denticulate, undulate, apex retuse; inner segments spreading obliquely, elliptic or narrowly obovate, 2.8--3 × 1.5--2.1 cm, margin denticulate, undulate. Stamens 0.8--1.2 cm; anthers white. Ovary 7--10 mm. Style branches pale blue; terminal lobes fimbriate. Capsule ellipsoid-cylindric, 2.5--3 × 1.2--1.5 cm, apex not beaked. Seeds dark brown, with small aril. Fl. Mar--Apr, fr. May--Jun. 2 n = 24*, 28, 34, 36, 54, 56*.
Open forest margins, wet grasslands; 500--800 m (2400--3400 m in SW China). Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Jiangsu, Jiangxi, Qinghai, Shaanxi, Shanxi, Sichuan, Xizang, Yunnan, Zhejiang [Japan, Myanmar].
This species is widely cultivated and it is possible that the high-elevation plants from SW China are not native but naturalized; however, they merit further investigation. White-flowered forms from Zhejiang have been recognized as Iris japonica f. pallescens P. L. Chiu & Y. T. Zhao (in Y. T. Zhao, Acta Phytotax. Sin. 18: 58. 1980).