echinacea, popular herbal remedy, or botanical, believed to benefit the immune system. It is used especially to alleviate common colds and the flu. Several controlled studies using it as a cold medicine have failed to find any benefit from its use, but a 2007 review of 14 different studies said that echinacea could have modest to marked effects against cold viruses. Echinacea is extracted from the roots and flowering tops of the purple coneflower (Echinacea angustifolia and E. purpurea).