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U.S. Forest Service


Our Native Irises: Blue Flag Irises

Iris virginica var. virginica: Southern Blue Flag Iris

The southern blue flag iris occurs from Virginia, south to Florida, and west to eastern Texas.

Iris virginica var. virginica. This view of Iris virginica var. virginica shows the typical veination and yellow signal that makes up the nectar guide for pollinators visiting each flower. Photo by Dr. Jean Everett, College of Charleston.

Map of the range of Iris virginica var. virginica in North America. Range map of Iris virginica var. virginica. Courtesy of the USDA PLANTS Database.

Iris virginica var. virginica has a light blue to deep violet, rarely white, flower. The sepals are spreading with darker blue to purple veins with a light yellow pubescent signal. Southern blue flag iris flowers in late spring. Flowers are a one- to two-flowered inflorescence on a barely- or non-branching stem. The plants are up to two feet tall. The weakly arching green leaves are two to three feet long and are burgundy colored at the base. The leaves arise from shallowly rooted, large, branching rhizomes that can form large clumps.

Iris virginica var. virginica is commonly found growing in wet ditches, swamps, wet meadows, marshes, stream edges and lake and pond shores.

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Iris virginica var. shrevei: Shreve's Iris

Shreve’s Iris occurs throughout the eastern United States except for New England, Georgia, and Florida. Iris shrevei occurs as far west as Nebraska and south to Texas.

Iris virginica var. shrevei. The variety of colors found in any given species of Iris can be aesthetically pleasing as is the case of this hue of light violet in Iris virginica var. shrevei. Photo by Thomas G. Barnes, University of Kentucky.

Map of the range of Iris virginica var. shrevei in North America. Range map of Iris virginica var. shrevei. Courtesy of the USDA PLANTS Database.

Iris virginica var. shrevei has a light blue to deep violet, rarely white, flower. The sepals are spreading with darker blue to purple veins with a light yellow pubescent signal. Shreve’s iris flowers in late spring. Flowers are a one- to two-flowered inflorescence on a stem that has one to two branches. The plants are up to three feet tall. The weakly arching green leaves are two to three feet long and are burgundy colored at the base. The leaves arise from shallowly rooted, large, branching rhizomes that can form large clumps.

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Iris virginica var. shrevei. In this specimen of Shreve’s iris, the delicate pinkish violet veining leads to a bold golden yellow signal that serve as the nectar guide for this flower. Photo by Thomas G. Barnes, University of Kentucky.

https://www.fs.usda.gov/wildflowers/beauty/iris/Blue_Flag/iris_virginica.shtml