The genus Echinopsis, in its wide sense, comprises somewhere between 100 - 150 species of cactus. There has been considerable disagreement amongst taxonomists as to how this group of species should be treated, with some favouring housing them all in the genus Echinopsis and others favouring separating them into several smaller genera. We are following the conclusions of Schlumpberger and Renner (Molecular Phylogenetics of Echinopsis (Cactaceae): Polyphyly at all levels and Convergent Evolution of Pollination Modes and Growth Forms; American Journal of Botany 99(8): 1335-1349. 2012) in which it is concluded that the most sensible answer is to group these specis into several distinct genera. If this species were to be retained in Echinopsis, it wuld be as Echinopsis pachanoi, or even as a variety of Echinopsis macrogona (see list of synonyms for authors)

Common Name: San Pedro Cactus

General Information

Trichocereus macrogonus pachanoi is a spiny (occasionally spine-free), evergreen, succulent shrubby to treelike cactus with many erect flexible branches arising mostly basally. It can grow around 3 - 6 metres tall, usually without distinct trunks, with cylindrical stems up to 5 metres long and 6 - 15cm in diameter[].
The San Pedro cactus has a long history of use, both as a medicine and for its effect upon the mind, senses and emotions.. Archaeological evidence has been found of its use for magical-religious purposes dating back to at least 1,500BC. Today's master shamans use San Pedro on altars ('mesas') erected for healing rites in order to treat enchantment and bad luck[]. The plant is frequently grown around or near houses in Peru and is used in many countries as an ornamental and in rituals[].
Trichocereus macrogonus pachanoi has a wide distribution and stable population. It is used as an ornamental and for magical-religious rites, but this impact is not considered to be a threat as the species is also cultivated for these purposes.The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2017)[].

Known Hazards

None known

Botanical References

Range

S. America - Peru to southern Ecuador

Habitat

Dry shrublands; at elevations from 2,000 - 3,200 metres[].

Properties

Conservation Status	Least Concern
Medicinal Rating
Other Uses Rating
Habit	Evergreen Shrub
Height	5.00 m
Growth Rate	Medium
Cultivation Status	Ornamental, Wild

Cultivation Details

In cultivation, Cactus plants generally will not succeed in moist climates. They usually require a sunny position in a well-drained, circumneutral soil and to be kept more or less dry in the dormant season[].

Edible Uses

None known

Medicinal

The San Pedro cactus has a very long history of use for shamanistic and medicinal purposes in S. America. It containd the alkaloid mescaline which has psychotomimetic effects similar to those of LSD and psilocybin, causing one to experience vivid colours and other enhancements of the senses. Several related cactus species also contain mescaline, but this species has been shown to have by far the highest concentrations, with selected cultivars containing up to 5% by dry weight[].
The plant is now used primarily for therapeutic purposes, which may include treatment of alcoholism and even mental illness. It is perceived to have great power in undoing witchcraft and fighting against various forms of sorcery. It is also used to treat ailments of the stomach, kidneys, liver, and blood, and to treat ulcers[, ].
A decoction of the stem is applied topically to prevent baldness[]. The pulp of the fresh stems is rubbed into the scalp to treat baldness and to strengthen the hair[].
A poultice made from the mashed and heated stem apices is used as a treatment for mumps, wounds and acne[, ].

An infusion of the flowers is used in the treatment of nervous conditions[, ].

Traditionally, in shamanistic practice, large pieces of the cactus stem are harvested and cut into slices as one would cut a loaf of bread. The pieces are boiled then simmered in water for as long as 7 hours, often combined with other plants such as Datura species[].
A strict diet should be followed prior to ingesting the plant: animal fat, grease, salt, chili peppers, and pieces of plants that entangle (vines such as beans and other legumes) are avoided[].
The preferred method of ingesting the preparation is through the nose. Tobacco is often used in combination with the cactus, for users believe that it enhances the effects of the cactus, clears the mind, and enhances several effects of the cactus such as visions, imagination, and sight[].
The psychotomimetic effects of the cactus result mainly from the alkaloid mescaline, which has psychotomimetic effects similar to those of LSD and psilocybin, causing one to experience vivid colours and other enhancements of the senses. One does not lose consciousness, nor does one actually hallucinate, but the effects on the mind are impressive, to say the least.
Mescaline is also found in the N. American peyote cactus (Lophophora williamsii). Concentrations of the alkaloid in the two cacti are similar according to some reports, although others say that this species contains only one-tenth as much mescaline as peyote. A related species, known as San Pedro macho (Trichocereus macrogonus) is said to have approximately the same mescaline content as peyote[].
The ingestion of San Pedro cactus at first causes nausea and vomiting but that these are seen as important in purging the sick person of impurities[], The second stage consists of three main parts: abnormal sensory phenomena, an alteration of one's conscious states and attitudes, and abnormal emotional states. It is characterized by euphoria and elation as well as pleasant fantasies. This is known as the psychic ‘intoxication’[].
Effects can be very strong and seen as deeply spiritual, or as deeply disturbing or even terrifying[]
Several forms of the San Pedro cactus are used by the curanderos, the most usual being those with seven ribs. Four-ribbed plants are rare but are believed to have special healing properties. Plants from the highlands are said to be the most potent, possibly as a result of climatic and soil factors[].

Agroforestry Uses:

The plant is used as a living fence in order to mark boundaries and act as a barrier[, ].

Other Uses

The mucilage from the stem is used as a hair shampoo[].

Propagation

Seed -

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