senna

Any of several plants, especially of the genus , in the pea family (see legume), mostly of subtropical and tropical regions. Many are used medicinally; some yield tanbark used in preparing leather. Some sennas are among the showiest flowering trees. In the eastern U.S., wild sennas ( and ) grow up to 4 ft (1.25 m) high and have showy spikes of yellow flowers. Some species are Old World shrubs or small trees.

Find more information on senna. Upgrade to Britannica Online for more on senna.