Black cohosh is a plant whose rhizome and root are used to relieve hot flashes and other symptoms of menopause. It is not known how black cohosh works or whether it acts like estrogen (a hormone needed to develop and maintain female sex characteristics and the growth of long bones). Historically, black cohosh has been used to treat many medical conditions. Also called black snakeroot, bugbane, bugwort, rattleroot, rattletop, rattleweed, and macrotys. Latin names: Actaea racemosa and Cimicifuga racemosa.