First described in 1560, Peyote is by far the best known and most widely utilized of the psychoactive cacti. Named after the Nahuatl (Aztec language) word for " cocoon silk " because of its wooly center tuft. A spineless, tufted, bluish-green, button shaped cactus with a large conical root. Native to the arid areas of central Mexico to northern Texas. The succulent crowns measure to 8 cm in diameter and are divided into 5 -14 rounded, vertical, more or less distinct ribs. Each tubercle has flat, small areolas with tufts of hair. Younger plants start with only 4 ribs, while old plants have up to 14. Peyote are one of the few Cacti to have spines only when they are seedlings.

Some tribes including the Huichol recognize two distinct forms. The Catus called Tzinouritehua-hikuri ( Peyote of the God ) is the larger, very bitter and of course more potent form. The Rhaitoumuanitari-hikuri ( Peyote of the Goddess ) form is said to be smaller and more palatable. It is now believed however that it is the same species but at different ages.

Peyote is one of the slowest growing plants in existence, taking 13 years or more to mature. Older cacti are generally much higher in alkaloids than young plants. The very oldest plants are worshiped by the Indians as "Father or Grandfather Peyote". They are often kept as amulets or placed on a crescent alter to be revered as a sacred object. A baseball sized Cactus can be well over 30 years old.

There have been over sixty alkaloids discovered in this plant which has been described as a " little green chemical factory ". This Cactus is known to contain 56 nitrogen containing compounds derived from a tyrosine base, as well as 20 tyramine-like alkaloids. Mescaline content usually ranges from about 3 - 6%, by dry weight, averaging around 4%, but is highly variable. Most of the alkaloids present can be classified as B-phenethylamines like mescaline or tetrahydroisoquinolines like hordenine. These chemicals differ in structure from LSD in that they don't have a complete indole ring. Mescaline content of fresh, undried cactus is reported at 0.4 %.