The leaves of Sanguinaria canadensis are quite variable in shape and size, and the scape and petals vary considerably in length. In some plants the petals are clearly differentiated into sets of two different sizes, but in others the differentiation is barely perceptible. Extremes of variation in these characters have been the bases for recognizing several forms, varieties, and even distinct species, but intermediates of all degrees are found and the variation is only loosely correlated with geography or habitat. Thus, it seems best to limit formal recognition to a single, quite variable species.
Although bloodroot is an ingredient of some compound cough remedies, it contains the poisonous alkaloid sanguinarine, and the U.S. Food and Drug Administration has characterized Sanguinaria canadensis as an unsafe herb (J. A. Duke 1985). Native Americans used it medicinally to treat ulcers and sores, croup, cramps, burns, tapeworms, fevers, diarrhea, and irregular periods, in cough syrups, as a spring emetic and blood purifier, to stop vomiting, and as a love charm, as well as in cermonial face paint (D. E. Moerman 1986).
