Sassafras

Sassafras is a species of tree native to North America, whose leaves are used to make filé powder in Creole cuisine, and whose roots were traditionally used to flavor root beer. Sassafras root was found to contain potentially dangerous levels of safrole, a potential carcinogen and toxin, so most commercial root beers now use synthetic sassafras (or related flavors, such as oil of wintergreen) or sassafras that has been chemically treated to remove safrole.