Feverfew (Tanacetum parthenium) is a weed, a medicinal herb and a bit of a toxin. This plant has the reputation of reducing fevers and migraines according to herbalists. It claims many other remedies. But, it also has had mixed results in the medical community and can cause nasty side effects. I plant it for its beauty. It is hardy and can spread like a weed if I am not careful. But my soil is mostly clay and shade, so it takes some real tenacity for any plant to take off.