Midewin National Tallgrass Prairie
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  • Wild Blue Flag Iris

    SCIENTIFIC NAME: Iris virginica shrevei

    COMMON NAMES: Wild Blue Flag Iris, Southern Blue Flag Iris, Shreve's Iris, Virginia Iris, Blue Flag

    BLOOM TIME: May, June, July


    • Plant of marshes and wet meadows.
    • Grows 1-3 ft. tall on solid stems.
    • Leaves are gray-green, sword-shaped, 20-40” long, & 3-4 leaves per stem.
    • 4 in. wide beautiful flowers are pale blue violet to purple in color with yellow blotch on 3 drooping petal-like sepals & beardless.
    • Grow in large outward expanding patches from rhizomes.
    • Yellow color help distinguish from Northern Blue Flag.
    • Grows 2-3 ft.. tall.
    • Seed pods often pull stalk of plant over to ground as pod finishes maturing.
    • Habitat: needs full sun & marshy areas to thrive, found in prairies, meadows along rivers, swamps, & ditches.
    • Common in Illinois.


    • The flowers are cross-pollinated by bumblebees & long-horned bees.
    • Butterflies & skippers also visit the flowers occasionally.
    • Some insects feed on Blue Flag Iris destructively. They include the weevil larvae feed on inside seed capsules, while Syrphid fly larvae & mealybug feed on the rhizomes.
    • Caterpillars of the Virginia Ctenucha moth, Agreeable Tiger Moth, & Iris Borer Moth also feed on these plants.
    • Mammalian herbivores rarely bother this plant because the foliage and rootstocks are somewhat toxic, causing irritation of the gastrointestinal tract.