POWO lists the homotypic synonyms Cereus pachanoi, Trichocereus pachanoi, Trichocereus macrogonus subsp. pachanoi, Trichocereus macrogonus var. pachanoi, and Trichocereus macrogonus subsp. sanpedro; and the heterotypic synonyms Echinopsis santaensis, Echinopsis schoenii, Trichocereus santaensis, Trichocereus schoenii, and Trichocereus torataensis. [https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:88444-2]
Native range
The species is native to Ecuador and Peru, and also occurs in Bolivia, Colombia, central Chile, the Canary Islands and mainland Spain, and is widely cultivated globally. [https://en.wikipedia.org/wiki/Trichocereus_macrogonus_var._pachanoi]
POWO gives the native range as 'S. Ecuador to Peru' (native to Ecuador and Peru). It is recorded as introduced in Bolivia, Chile (Central), Colombia, the Canary Islands, and Spain. [https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:88444-2]
Habitat
It grows in the Andes at roughly 2,000-3,000 m (about 6,600-9,800 ft) elevation, in the seasonally dry tropical biome (mountainous, semi-arid conditions). [https://en.wikipedia.org/wiki/Echinopsis_pachanoi; https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:88444-2; https://naisma.org/2026/02/03/echinopsis-pachanoi-the-san-pedro-cactus-biology-cultural-history-and-environmental-considerations/]
Vegetative description: a fast-growing columnar cactus reaching 3-6 m (10-20 ft, tallest recorded 12.2 m), stems 6-15 cm in diameter, light to dark green and sometimes glaucous, usually 6-8 ribs, areoles whitish and spaced about 2 cm apart, with up to about seven yellow-to-brown spines each up to 2 cm long (often few or absent). [https://en.wikipedia.org/wiki/Echinopsis_pachanoi]
Flowers are nocturnal (night-blooming) and white, borne near the stem tips, about 19-24 cm long and up to 20 cm in diameter, lasting roughly two days, with black hairs along the thick floral tube. [https://en.wikipedia.org/wiki/Echinopsis_pachanoi]
History
The species epithet 'pachanoi' honors Abelardo Pachano; the type material was collected by J.N. Rose, A. Pachano and George Rose (collection no. 22806) near Cuenca, Ecuador, with the holotype at the New York Botanical Garden herbarium (NY). [https://trichocereus.net/trichocereus-pachanoi-britton-and-rose-1920-echinopsis-pachanoi/; https://en.wikipedia.org/wiki/Echinopsis_pachanoi]
