The root is smaller than that of the iris, reddish outside and white inside, knotty, and fibrous. To be of use, it must be new, heavy, and of a dusky red color. Its odor resembles that of fig leaves. Its taste is aromatic, accompanied with some acrimony.
The contrayerva root was formerly considered by many writers to be one of the best anti-epidemics known. Dr. Nathaniel Hodges (1629–1688), in his treatise of the Great Plague of London (Loimologia; published in 1672), had a recipe which he said was very successful, and of which this root was one of the chief ingredients.