Blue flag

Blue flag, or Iris versicolor, is a perennial wild iris indigenous to eastern North America named after the Greek goddess of the rainbow. The plant looks very similar to the common garden-variety iris except that the flowers, which are a vivid bright blue, are slightly smaller.

Blue flag is known by many other common names that reflect its historical significance and reputed medicinal properties. For instance, it is sometimes referred to as liver lily because the dried rhizome is a traditional remedy to cleanse the blood and liver. Since early European settlers thought the plant closely resembled its European cousin, which inspired the design of the official emblem of French royalty, blue flag is sometimes called fleur-de-lis. Other common names include snake lily and water lily, a reference to the plant’s ability to thrive in shallow water.

In Native American medicine, blue flag was used internally to treat liver and blood disorders, and externally to treat sprains, bruises and inflammation, including pain and swelling associated with arthritis and rheumatism. These treatments were likely very effective due to the chemical composition of the plant. For instance, the root contains a glycoside called iridin that earned blue flag a place in the U.S. Pharmacopeia as a diuretic and liver stimulant. The root also contains salicylic acid, the basic component of aspirin.

In high doses, oral preparations made from the root may cause vomiting. Most herbalists suggest a tea or infusion made from ½ teaspoon dried root, taken three times per day, as a safe, therapeutic dose. However, this herb should not be used during pregnancy or lactation. Poultices and other topical applications of blue flag root are considered non-toxic, as are homeopathic preparations.