Iris versicolor, also commonly known as the Blue flag, Harlequin Blueflag, Larger Blue Flag, Northern Blue Flag, and other variations of those names, is a species of Iris native to North America where it is common in sedge meadows, marshes, and along streambanks and shores. The flower get its name Versicolor from the Greek word Rainbow, in allusion to the prismatic colors of the species.
I. versicolor is a flowering herbaceous perennial plant, growing 10–80 centimetres high. This iris tends to form large clumps from thick, creeping rhizomes. The unwinged, erect stems generally have basal leaves that are more than 1 cm wide. Leaves are folded on the midribs so that they form an overlapping flat fan. 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. Fruit is a 3-celled, bluntly angled capsule. The large seeds can be observed floating in fall.
Chemical constituents 
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 cultivated flower for 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.
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