Chronic use of traditional herbal remedies containing Aristolochia species (Aristolochiaceae) has been linked to kidney failure and possibly cancer in humans, attributable to aristolochic acid content. Asarum canadense (wild ginger) is believed to contain aristolochic acids and has been banned from commerce; however, wild ginger has a long history of safe folk use as food and medicine, and numerous books for the public describe it as edible. We sampled rhizomes from across its U.S. range, as well as the rhizomes of other North American species of Aristolochiaceae, and surveyed them for the presence of aristolochic acids I and II (AA I and AA II) by HPLC. AA I and II were present in significant quantities (maximum values of 0.39% and 0.66% respectively) in Aristolochia species and Hexastylis arifolia. AA I alone was detected in all samples of Asarum canadense and in minute quantities in Asarum caudatum, though not in Asarum wagneri. Concentrations in A. canadense were highly variable, in one instance reaching 0.037% of dry weight. The highest amounts were found in small populations under environmental pressure; also, concentrations were higher in samples from the northeastern U.S. and North Carolina than in those from the upper Midwest and South Carolina. It is possible that long-term consumption of material from high-AA populations would pose some risk of harm to susceptible individuals. Pending better understanding of safe dosage limits and the distribution of chemical races, a conservative approach to food safety suggests that consumption of Asarum canadense should not be encouraged in field guides or botany classes.

Key words: Aristolochiaceae, aristolochic acid, Asarum canadense, herbal medicine, Hexastylis