Culver's Root, Veronicastrum virginicum
This tall and graceful member of the snapdragon family does well in moist conditions in full sun and even in partial shade. Its name refers to the 18th century physican who documented the root’s properties as a laxative. Culver’s Root can reach up to 7 feet in full sun. Its height makes it ideal at the back of the border in a garden; its blooming period can last from late spring to late summer, and draws butterflies to its long racemes of white flowers.