Harlequin Blue Flagnative

Field guide

Iris versicolor is a rhizomatous wetland perennial of eastern North America forming clumps of sword-shaped blue-green leaves to 2–3 ft. In late spring it bears 3–5 violet-blue flowers with bold purple veins and a greenish-yellow signal on the falls. It thrives in moist to wet, acidic soils and tolerates several inches of standing water, making it a mainstay of rain gardens, pond margins and wet meadows, naturalizing by rhizome and self-seeding. It is distinguished from I. virginica by its greenish-yellow (not bright-yellow, hairless) signal and by leaves that do not overtop the flowers. The rhizomes are poisonous and were used medicinally—carefully—by Native peoples.

Gardener's notes

Give blue flag the wettest, sunniest spot you've got—a downspout outfall or rain-garden floor is perfect. Leave the clumps undisturbed and they'll knit into a colony; divide only when the center thins. Skip fertilizer and never let it bake bone-dry in summer.

Ecology

• Pollinators: bumblebees, long-tongued bees, hummingbird
• Larval host for: Virginia ctenucha moth (reported)
• Birds: hummingbird nectar

Care this season

• Watering: establishment only in a moist site; never let it bake bone-dry in summer
• Pests: iris borer (less than bearded), snails, muskrats eat rhizomes
• Toxicity: rhizomes toxic to humans/livestock; skin irritant

Sources

• Iris versicolor — Lady Bird Johnson Wildflower Center
• Iris versicolor — NC State Extension
• Iris versicolor — Missouri Botanical Garden