Feverfew (Tanacetum parthenium; syn. Chrysanthemum parthenium) is a traditional medicinal herb which is found in many old gardens, and is also occasionally grown for ornament. 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. Feverfew has been used for reducing fever, for treating headaches, arthritis and digestive problems. It is hypothesized that by inhibiting the release of serotonin and prostaglandins, both of which are believed to aid the onset of migraines, feverfew limits the inflammation of blood vessels in the head. This would, in theory, stop the blood vessel spasm which is believed to contribute to headaches.