Yellow flag iris (Iris pseudacorus) is an herbaceous perennial that can grow up to 3- to 4-feet tall as it invades wetlands. This perennial is native to Europe, Asia, the Middle East, and Northern Africa, but has become naturalized in much of North America, especially in the eastern United States. Yellow flag iris is found in wet soils, usually forming large colonies along streams, ponds, and marshes eventually displacing native vegetation.
The rhizomes and seeds of this aquatic species can be transported downstream, further spreading the plant. Despite its wetland preference, yellow flag iris rhizomes can survive periods of severe drought. The showy, typically yellow flowers bloom from April to June and unlike other iris species, are beardless. Flowers are on erect peduncles with several occurring per stem. Sepals often have purple, brown, or red veins on their yellow surface. The leaves are broad, stiff, erect, glaucous (grayish-green or blue color), and sword-shaped. Seeds of this plant contain glycosides, which are toxic to grazing animals. Caution should be used when handling this plant because it has been known to cause skin irritation. Yellow flag iris has been observed in the Mountains, Piedmont, and Coastal Plain of North Carolina.
Fact Sheet: Yellowflag Iris