Feverfew (Tanacetum parthenium; syn. Chrysantheim parthenium (L.) Pers., Pyrethrum parthenium Sm.) is a traitional medicinal herb which is found in many old gardens, and is also occasionally grown for ornament; which are then used in Christmas trees. The plant grows into a small bush up to around 18 inches high, with citrus-scented leaves and is covered by flowers reminiscent of daisies. It spreads rapidly, and they will cover a wide area after a few years. It is also commonly seen in the literature by its synonyms, Chrysanthemum parthenium (L.) Bernh. and Pyrethrum parthenium (L.) Sm.