Iris, any of a genus (Iris) of perennial herbaceous plants with intricate and colorful flowers, found in temperate parts of Europe, Asia, Africa, and North America. The iris is a member of the family Iridaceae, which includes the crocus, freesia, and gladiolus. Irises grow from rhizomes (swollen underground stems) or from bulbs. Many varieties have been cultivated for their 3-part flowers, on which the fleur-de-lis (French: “flower of the lily”) of heraldry was based. The dried rhizome of certain irises is called orrisroot.