What is the name of the legal mescaline-containing cactus?
Most commonly, you are referring to Trichocereus pachanoi, aka “San Pedro”. Various other Trichocerei have been shown to contain mescaline, however, and there have been been informal reports of usage of T. peruvianus and what we suspect is T. macrogonus as well. T. pachanoi is employed as a grafting stock, landscape plant, ornamental accent, and (in South America) as hedging and fencing. It has wonderful 9″ night-blooming flowers, in season. It is amenable to pot-culture (i.e., growing it in a clay pot on your patio). It is legal to own, but illegal to consume or process into mescaline.