Muira Puama (Lyriosma ovata), also called potentwood or marapuama, has been used for centuries in South America to treat sexual dysfunctions as well as to increase desire – as “potentwood” might suggest! It’s actually the bark and/or root of a tree. As such, it must be decocted (boiled for a while) in order to exctract the beneficial substances.
As far as actual effects go, it appears to be similar to yohimbe but milder and without yohimbe’s side effects. It hasn’t been analyzed quite as much as the African plant, and I suspect pharmacological studies in the future will reveal very interesting facts. The one study I’m aware of, that took place in 1990, was quite promising.