Historically, blue flag was an important herb to many Native American tribes,
including the Mohawk, Seneca, Ojibwe, Potawatami, Chippewa and Cree.
While the leaves of the plant were used for basket weaving and the
flowers to produce a light dye, the roots were dried and decocted to
produce poultices to ease pain and inflammation associated with
arthritis as well as bruises, psoriasis and other skin conditions. The
effects were likely due to the astringency of tannins and the presence
of salicylic acid, which is a chemical precursor to aspirin.
