Frangula.

Buckthorn, Rhamnus frangula, grows in wet places throughout Europe, Siberian Asia, and the Northern African Coast. From a very early date it has been known as a cathartic as well as a coloring agent. A decoction of the bark has been in domestic use both as a dye for cotton, wool, and silk fabrics, and as a cathartic, in which (latter) direction it is very effective. No written professional record antedates its domestic use, and perhaps as a "rheumatic remedy" it has no domestic superior.

The History of the Vegetable Drugs of the U.S.P., 1911, was written by John Uri Lloyd.