Rhizomatous plant 60-90 cm. Leaves sword-shaped, with prominent midrib, 1.0-1.5 cm broad. Stem shorter than leaves. Flowers 2-4, large, dark purple or violet, terminal. V - May to October. Fl - June-July. Fr - September. P - by seed and division. Known from Japan as an ancestor of the numerous cultivars of Japanese irises. Z 5 (4).

Siberia (southern regions), Far East, northeastern China, Korea and Japan. Moist meadow slopes, fluvial plains with rich lime-free soil.