false indigo

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A shrub (Amorpha fruticosa) of eastern North America, having compound leaves with numerous leaflets and long clusters of purplish flowers.
2. n. A plant (Baptisia australis) of the southeast United States, having compound leaves with three leaflets and deep blue or purplish flowers.

WordNet 3.0

1. n. any of several plants of the genus Baptisia
2. n. dense shrub of moist riverbanks and flood plains of the eastern United States having attractive fragrant foliage and dense racemes of dark purple flowers
3. n. an erect to spreading hairy shrub of the Pacific coast of the United States having racemes of red to indigo flowers