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Blue Flag

  • Iris versicolor L.
  • Iridaceae
  • Iris family

Common Names

herbsBlue Iris
herbsFlag lily
herbsFlower de-luce
herbsLiver lily
herbsPoison flag
herbsSnake lily
herbsWater flag
herbsWater lily

Parts Usually Used


Description of Plant(s) and Culture

Blue flag is a perennial, 1-3 ft. in height. and grows erect, has narrow, sword-shaped leaves and, from May to July, violet blue flowers streaked with yellow, green, and white. The sword-like leaves are similar to those of garden irises, with flowers violet-blue, sepals violet at outer edge; veins prominent, sheaths papery. It prefers wet, swampy locations and is found in such spots from Canada to Florida and west to Arkansas. Wet meadows, moist soil. Native to America, it is both beautiful and potentially poisonous. The flowers yield a blue infusion which can substitute for litmus paper in testing for acids and alkalines, but it is the root which has been most widely used. When fresh, the root has a slight odor and a pungent, acrid, and nauseous taste, a natural warming of the actively poisonous nature of the fresh root. Although the Indians had some uses for the fresh root, it was usually collected in autumn and dried.

Blue flag is an iris similar in foliage appearance to the sweet flag, Acorus calamus. Unfortunately for some, it has quite different properties and if mistakenly used internally as one might sweet flag, the results can be disastrous.

Medicinal Properties

Anti-inflammatory, alterative, cathartic, diuretic, laxative, resolvent, sialagogue, stimulant, vermifuge

Legends, Myths and Stories

About 800 species belonging to more than 50 genera have been described from temperate to tropical climates, mostly from South Africa and tropical America.


American Indians poulticed the root on swellings, sores, wounds, bruises, ulcers, takes away freckles, rheumatism; internally root tea was used as a strong laxative, emetic, and to stimulate bile flow. Useful in cancer, dropsy, impurity of blood, syphilis, skin diseases, liver troubles, and as a laxative.


This herb is potentially fatal. Could cause death or other serious consequences. Its use is not recommended without constant medical supervision.

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