black cohosh

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An eastern North American perennial herb (Cimicifuga racemosa) having large, pinnately compound leaves and racemes of small white flowers. Also called black snakeroot.

Wiktionary

1. n. A smooth herb, Actaea racemosa, marketed for medicinal use.

WordNet 3.0

1. n. North American bugbane found from Maine and Ontario to Wisconsin and south to Georgia