Echinopsis macrogona,synonymTrichocereus macrogonus, is a species ofcactus found in Bolivia and Peru.[2]Echinopsis macrogona is one of a number of similar species that may be calledSan Pedro cactus. Indigenous names includeachuma andhuachuma, although these too may be applied to similar species.[citation needed]
The species has erect stems, 2.5–5 m (8–16 ft) tall, with branches generally with a diameter of 6–15 cm (2–6 in), occasionally more. At the base of the stem there are usually seven or eight ribs. Generally the species has relatively few ribs, typically six to eight, occasionally five or nine. The circular areoles are 6 mm (0.2 in) across, grey or dark brown, with needle-like spines, and are spaced more than 2.5 cm (1.0 in) apart. The number and length of the spines varies. Older areoles may have up to 20, with three or four prominent, longer and more robust central spines up to 5 cm (2.0 in) long. The spines are darker at the end. The flowers are carried mostly near the top of the stems. In total they may be up to 21 cm (8.3 in) long. Thetepals may be pale yellow or yellowish green, rarely pink. The small seeds are broadly ovoid, 0.9–1.1 mm (0.04–0.04 in) long.[3]
The first description asCereus macrogonus byJoseph zu Salm-Reifferscheidt-Dyck was published in 1850.[2][4] The specific epithetmacrogonus is derived from the Greek wordsmakros for 'large' andgonia for 'edge' and refers to the ribs of the species.[citation needed] Vincenzo Riccobono placed the species in the genusTrichocereus in 1909.[2][5] Heimo Friedrich and Gordon Douglas Rowley placed the species in the genusEchinopsis in 1974 asEchinopsis macrogona.[2]
Other names have been applied toEchinopsis macrogona. The taxonomy of the species was revised in 2012 by Sofía Albesiano and Roberto Kiesling when the species was treated in the genusTrichocereus. In particular, they sankTrichocereus peruvianus andTrichocereus pachanoi intoT. macrogonus, treatingT. pachanoi asT. macrogonus var.pachanoi. The number and size of the spines was regarded as a distinguishing feature of the two varieties, although this was noted to be a variable character, influenced by environmental conditions: cultivated plants develop more spines when moved to sunnier positions.[6] As of 2023[update],Plants of the World Online treatedT. peruvianus orEchinopsis peruviana as a synonym ofE. macrogona,[2] but treatedT. pachanoi as the separate speciesEchinopsis pachanoi.[7]
As of November 2025[update], Plants of the World Online regarded the species as native toBolivia andPeru, and introduced to theBalearic Islands, theCanary Islands,Colombia, and mainland Spain.[2] However, plants are widely cultivated making the true origins of the species difficult to determine. It has been speculated that the original native distribution may only be the high valleys of Peru and perhaps also northwestern Bolivia.[6]
This species of cactus has been used by humans for several millennia. The oldest find was located in theGuitarrero Cave, in the Áncash region in Peru. In this cave, inhabited continuously since 8600 BCE, a high concentration ofE. macrogona pollen from the oldest phase of human occupation has been detected, as well as some fragments of cactus, which would testify to the intentional introduction of this plant inside the cave.[8] Ritual uses of the species are depicted on pre-Columbian Peruvian ceramics and other archaeological objects, with one use dated to about 1300 BCE. Indigenous names includeachuma andhuachuma.[6]
Echinocereus macrogona is one of a number of species native to the Andes that have been reported to contain the psychoactive alkaloidmescaline (reports may use various synonyms of the currently accepted names).[9] Another species isEchinopsis lageniformis. All the columnar species thought to be psychoactive have been called "San Pedro" in Spanish. Reported concentrations of mescaline vary widely, with causes suggested to include: taxonomic uncertainty leading to difficulties in identification; genetic differences between species and within populations; environmental factors, such as temperature and water availability, affecting plants during growth; and variations in laboratory techniques.[10]
Some studies have reported no mescaline content in wild-harvested Peruvian specimens ofE. macrogona,[11] and in plants grown in Europe.[12] In those studies that have compared different species andcultivars, the concentrations found were very variable. In samples identified asEchinopsis pachanoi, the lowest found was 0.4% of dry weight compared to 4.7% for a form on sale in traditional Peruvian shamans' markets.[10] The plants used by shamans are likely to be cultivars they have selected for their mescaline content.[6] Mescaline is not evenly distributed within single specimens ofE. lageniformis.[13]
^Salm-Reifferscheidt, Joseph; Georgi, Carl (1850).Cacteae in horto Dyckensi cultae anno 1849, secundum tribus et genera digestae : additis adnotationibus botanicis characteribusque specierum in enumeratione diagnostica cactearum Doct. Pfeifferi non descriptarum /. Bonnae: Apud Henry & Cohen, typis C. Georgii.doi:10.5962/bhl.title.120333.hdl:2027/mdp.39015061403484.
^abOgunbodede, Olabode; McCombs, Douglas; Trout, Keeper; Daley, Paul & Terry, Martin (2010). "New mescaline concentrations from 14 taxa/cultivars ofEchinopsis spp. (Cactaceae) ("San Pedro") and their relevance to shamanic practice".Journal of Ethnopharmacology.131 (2):356–362.doi:10.1016/j.jep.2010.07.021.PMID20637277.
^Djerassi, Carl; Liu, L.H.; Farkas, E.; Lippman, A.E.; Lemin, A.J.; Geller, L.E.; McDonald, R.N. & Taylor, B.J. (1955). "Terpenoids. XI.1 Investigation of Nine Cactus Species. Isolation of Two New Triterpenes, Stellatogenin and Machaeric Acid".Journal of the American Chemical Society.77 (5):1200–1203.Bibcode:1955JAChS..77.1200D.doi:10.1021/ja01610a033.
^Agurell, S. (1969), "Cactaceae alkaloids. I",Lloydia,32 (2):206–216,PMID5812246
.jpg)
