What type of cactus is pictured?

Echinopsis pachanoi — known as San Pedro cactus — is a fast-growing columnar cactus native to the Andes Mountains at 2,000–3,000 m (6,600–9,800 ft) in altitude. It is found in Argentina, Bolivia, Chile, Ecuador and Peru, and it is cultivated in other parts of the world.

Uses for the cactus include traditional medicine and traditional veterinary medicine, and it is widely grown as an ornamental cactus. It has been used for healing and religious divination in the Andes Mountains region for over 3,000 years. It is sometimes confused with its close relative Echinopsis peruviana (Peruvian torch cactus).

Echinopsis pachanoi is known by many names throughout South America such as achuma, huachuma, wachuma, aguacolla, hahuacollay, or giganton.

Echinopsis pachanoi has a long history of being used in Andean traditional medicine. Archeological studies have found evidence of use going back two thousand years, to Moche culture. Although Roman Catholic church authorities after the Spanish conquest attempted to suppress its use, this failed, as shown by the Christian element in the common name "San Pedro cactus" – Saint Peter cactus. The name is attributed to the belief that just as St Peter holds the keys to heaven, the effects of the cactus allow users "to reach heaven while still on earth."