Euonymus atropurpureus and Euonymus americanus are probably collected indiscriminately, both varieties being known by the common name Wahoo. The bark of the root is the part used. This remedy, in the form of a decoction, was once a favorite in domestic medication, and was introduced from thence to the regular medical profession, as were other American remedies of like nature. It occupied a place in all the early domestic works on medicine, and seems to be alike credited to the American Indians and the early settlers. In Eclectic medication wahoo has been a favorite since the days of Dr. Beach. Under the names "nine barks" or "seven barks" it has a domestic record transplanted to proprietary remedies that use these titles. The Eclectic "concentration" euonymin has been conspicuous in England, but has since fallen into disuse. (See Bulletin of the Lloyd Library, No. XII, The Eclectic Resins, Resinoids, Oleo-Resins, and Concentrated Principles. (http://www.swsbm.com/ManualsOther/Eclectic_Alkaloids-Lloyd.pdf))
The History of the Vegetable Drugs of the U.S.P., 1911, was written by John Uri Lloyd.