blue flag iris

noun

variants or blue flag

plural blue flag irises or blue flags

: any of several irises of the U.S. and Canada that have pale blue to deep violet flowers and that typically grow in moist habitats

Besides the wild blue flag iris …, there are many other varieties that can be grown in your garden.

—Keith Fuller

especially : either of two common irises (Iris versicolor and I. virginica) chiefly of the eastern and central U.S. that are sometimes grown for their ornamental flowers

A true water-lover, the blue flag (Iris versicolor) produces beardless blue flowers in May and June. … Plant this attractive native iris at the edge of ponds or in moist soil.

—Sue Kittek

Examples of blue flag iris in a Sentence

Recent Examples on the Web

Adding flower beds filled with water-loving plants such as daylilies, blue flag irises, and button bushes is an attractive solution for soggy areas. —Mary Marlowe Leverette, Southern Living, 7 Mar. 2026

Word History

First Known Use

1732, in the meaning defined above

Rhymes for blue flag iris

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Medical Definition

blue flag iris

noun

-ˈflag- 

variants or blue flag

1

: either of two common blue-flowered irises (Iris versicolor and I. virginica) of the eastern and central United States with rhizomes formerly used medicinally as a cathartic and emetic

2

or blue flag root : the dried rhizome of a blue flag iris