A small, spineless cactus (Lophophora williamsii) found from southwest United States to central Mexico that produces buttonlike tubercles that can be chewed for its psychedelic effect, primarily from the drug mescaline.
User Defined Definitions
"a small spineless globe-shaped cactus; source of mescal buttons"
"the hallucinatory alkaloid that is the active agent in mescal buttons"