Iris versicolor is also commonly known as the blue flag, harlequin blueflag, larger blue flag, northern blue flag, and poison flag, plus other variations of these names, and in Britain and Ireland as purple iris.

It is a species of Iris native to North America, in the Eastern United States and Eastern Canada. It is common in sedge meadows, marshes, and along streambanks and shores. The specific epithet versicolor means "variously colored".

Iris versicolor is a flowering herbaceous perennial plant, growing 10-80 cm (4-31 in) high. It tends to form large clumps from thick, creeping rhizomes. The well developed blue flower has 6 petals and sepals spread out nearly flat and have two forms. The longer sepals are hairless and have a greenish-yellow blotch at their base. The inferior ovary is bluntly angled. Flowers are usually light to deep blue (purple and violet are not uncommon) and bloom during May to July.

The species has been implicated in several poisoning cases of humans and animals who consumed the rhizomes, which have been found to contain a glycoside, iridin. The sap can cause dermatitis in susceptible individuals.

The iris is the official state flower of the U.S. state of Tennessee. This designation was made in 1933 by the state legislature. Although the law does not specifically define a type of iris, it is generally accepted that the purple iris is the state flower.

The blue flag is the provincial flower of Quebec, having replaced the Madonna lily which is not native to the province.

The Purple Iris is the official flower of Kappa Pi International Honorary Art Fraternity.

Seeds are large and fresh.

Type: Hardy perennial

Hardiness zones: 3-9

Seeds per packet: 15