Petasites hybridus, the butterbur, is a species of herbaceous perennial flowering plant in the family Asteraceae native to Europe and northern Asia. Although used over centuries in traditional medicine to treat various disorders and sometimes sold as a dietary supplement, it has no approved medical uses. Concerns about the potential toxic effects of pyrrolizidine alkaloids limit its use in human and animal studies. This P. hybridus inflorescence was photographed in a forest near Keila in northwestern Estonia.Photograph credit: Ivar Leidus