Drive by any marsh in northeastern U.S. or eastern Canada in June or July, and you’re likely to be greeted by a carpet of purple blooms swaying above sword-like foliage. Iris versicolor, commonly known as blue flag iris, northern blue flag, and harlequin blue flag, is a beardless iris species that grows native to wetland environments throughout the northern tier of the United States from Minnesota and Illinois eastward, as well as the eastern half of Canada. While not historically grown as a garden iris, I. versicolor is gaining popularity with hybridizers who are eager to explore the possibilities of its genetic compatibility with a wide variety of other beardless iris types.
Iris versicolor is a very adaptable iris for northern climates. Modern cultivars beautifully enhance home gardens when provided with ample space and water. Blue flag iris blooms well in filtered to full sunlight and humus-rich soil. With a typical bloom height of 2-3′, I. versicolor works particularly well in mid-border when combined with other moisture-loving plants. While the native species is most often found in shades of purple, lavender, and sometimes white, hybridizers have expanded the offerings of Iris versicolor to include pinks, near-blacks, and striped varieties. Some of these blue flag iris cultivars can be viewed in the slideshow, Iris versicolor: Beauty of the Northern Wetlands.
The pinkish-white rhizomes from which Iris versicolor grows were once used medicinally by Native Americans. The dried rhizomes may still be in use today for various skin diseases, bile problems, and liver disorders. Some people, however, may be sensitive to iris parts and develop dermatitis after its use.
One of the most interesting characteristics of blue flag iris is its ability to breed successfully with a number of other beardless iris types, resulting in exciting new hybrid iris creations with enticing new forms, colors, and patterns. These wide crosses using Iris versicolor are adaptable to different climates and growing conditions in which I. versicolor itself may not flourish. Among these crosses are I. versicolor X I. ensata (versata), I. versicolor X I. virginica (I. x robusta), I. versicolor X I. laevigata (versilaev), I sanguinea X I. versicolor, Siberian X I. versicolor, and I. pseudacorus X I. versicolor. More intriguing advances are bound to come from these and other crosses with the blue flag iris.
The humble blue flag iris may well hold the future of beardless iris advancement in its genetic code. For all its simple grace and swampy beginnings, this is not a plant to underestimate in its significance.
Christine Haughton, Blue Flag, Purple Sage Botanicals
PLANTS Database, PLANTS Profile for Iris versicolor (harlequin blueflag) USDA PLANTS, USDA Natural Resources Conservation Service
Robert Pries, SpecVersicolor , The American Iris Society Iris Encyclopedia