Trichocereus macrogonus aka San Pedro Cactus

Trichocereus macrogonus is a cactus from western and southern Peru to Bolivia. Its family is Cactaceae, the cactus family. Some sources use the name Echinopsis macrogona. Others call it Cereus macrogonus. Useful Tropical Plants calls it San Pedro Macho. These names stem from changes in how botanists group these cacti. RHS treats Trichocereus macrogonus as another name for Echinopsis macrogona. The plant is not native to Britain or Ireland.

This evergreen succulent can grow as a shrub or small tree. Its branches may stand upright or lie along the ground. The thick, round stems bear spines. Plants reach about 3–13 feet [1–4 metres] tall. Useful Tropical Plants also gives a height of 10 feet [3 metres]. Stems measure about 0.2–0.7 feet [0.06–0.20 metres] across. Its many branches give it a shrub-like or tree-like shape. The supplied account does not describe its flowers or fruit. It says the plant cannot fertilise itself.

In the wild, it grows in dry Andean valley shrubland. The habitat account gives a height above sea level of 9,843–11,483 feet [3,000–3,500 metres]. A second passage suggests it may come from lower land. This band lies in Peru at 6,562–9,843 feet [2,000–3,000 metres]. Its native climate is semi-arid, or quite dry. It grows at mid to high levels above the sea. The species account says it needs hot summers. It gives a minimum yearly mean temperature of 10°C. Brief cold spells may reach −9°C in fairly dry conditions. This does not show that it can stand long freezes. Nor does it show that it can stand wet winters.

People grow this cactus in Bolivia, Colombia, Chile, Ecuador and Peru. They grow it for its looks and as a living fence. They also grow it for use in healing and religious rites. It has alkaloids, a group of compounds linked to mescaline. These can change thoughts, senses and feelings. Useful Tropical Plants lists no food uses for this species. It reports no known hazards, but that does not mean it is safe to eat. The supplied account gives no pest or disease details for this species.

Useful Tropical Plants gives its 2017 IUCN status as Least Concern. It says the plant has a broad range. Its numbers seem stable, but it is not abundant where it grows. The same account reports none within protected areas. It also notes that people collect or use the cactus for effects that can cause hallucinations.