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Wetland Plants and Plant Communities of Minnesota and Wisconsin


(Iris versicolor L.)

Blue flag iris

IRIS FAMILY (Iridaceae)


FIELD CHARACTERISTICS: A perennial herb, usually 10-80 cm. 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 flower 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 and in bloom during May to July. Fruit is a 3-celled, bluntly angled capsule. The large seeds can be observed floating in the fall.

A similar species, I. virginica, can be distinguished by its cauline (stem) leaves that often exceed the inflorescence whereas the cauline leaves of I. versicolor are usually shorter than or equal to the height of the inflorescence.

ECOLOGICAL NOTES: Blue flag iris is common in sedge meadows, marshes, and along streambanks and shores. Iris versicolor tends to be more northern in its regional distribution, while I. virginica is more southern. There is some debate concerning the taxonomic status of I. versicolor. See Swink and Wilhelm (1994) for a brief discussion.

SOURCE: Gleason and Cronquist (1991); Swink and Wilhelm (1994); and Voss (1972).

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