The African tree whose bark contains yohimbine is yohimbe. Its scientific name is Pausinystalia johimbe, a tree native mainly to the rainforests of Cameroon and Gabon.
Yohimbine is one of dozens of indole alkaloids found in the bark. It attracted medical interest because it can affect adrenergic receptors and has been studied for erectile dysfunction. Yohimbe bark itself is a complex herbal mixture, while yohimbine is the purified compound; the two names are often incorrectly treated as synonyms.
The bark has traditionally been harvested for medicinal and aphrodisiac preparations. Heavy demand has caused overharvesting, and collection can kill the tree because the bark is stripped from its trunk. Adulteration is also a concern: bark from related species may be mixed into commercial supplies but contain little yohimbine.
A useful distinction is that yohimbe refers primarily to the tree or its bark preparation, whereas yohimbine refers to the specific alkaloid. Pharmaceutical products generally use yohimbine hydrochloride rather than unstandardized bark.