At first, this bit of German doggerel might seem to have little relation to a West African tree, but it is just such a plant whose bark, known as yohimbe, has long been valued as an aphrodisiac. The tree, known as Pausinystalia yohimba Pierre, a member of the family Rubiaceae, is native to Cameroon, Gabon, and Congo. Its bark contains up to about 6 percent of a mixture of alkaloids, the principal one being yohimbine.1