Origin and Habitat: Garden origin (Nursery produced cultivar). The wild form is of Mountains of Peru, Ecuador, Bolivia and northern Argentina. It is subspontaneous in several South American and in some tropical countries in other continents.

• Echinopsis pachanoi f. cristata aurea hort.
• Trichocereus pachanoi f. cristata aurea hort.

• Echinopsis pachanoi (Britton & Rose) H.Friedrich & G.D.Rowley
• Cereus pachanoi (Britton & Rose) Werderm. in Backeb.
• Trichocereus pachanoi Britton & Rose
• Echinopsis pachanoi f. cristata aurea hort.
• Trichocereus pachanoi f. cristata aurea hort.
• Echinopsis pachanoi f. cristata hort.
• Trichocereus pachanoi f. cristata hort.
• Echinopsis pachanoi f. quadricostatus hort.
• Trichocereus pachanoi f. quadricostatus hort.

• Echinopsis pachanoi f. monstruosa cv. Gianfra
• Trichocereus pachanoi f. mostruosa hort.

Description: The typical San Pedro cactus (Echinopsis pachanoiSN|26988]]SN|8470]] syn: Trichocereus pachanoiSN|8471]]SN|8471]]) is a multi-stemmed “organ-pipe cactus” with light green stems (slightly glaucous when young, dark green in age) that that forms a small tree 3 to 6 meters tall by 1,8 m spread, with several branches, usually extending from the base
Forma cristata aurea (yellow crested form): The yellow schizochromic crested form (Echinopsis pachanoi f. cristata aureaSN|8470]]SN|26988]]) has bright yellow crested stems due to the absence (or reduced production) of chlorophyll pigments: every other pigment is present at normal levels, the dominant green colouration is lost, but will still more than likely have normal other pigments that give the yellow overall appearance of the stem. This form with yellow fan shaped stems is very attractive and highly prized. This schizochromic form is almost always seen grafted on stronger columnar species, and cannot can be grown on its own roots. However some clones have enough chlorophyll in their tissues and can be grown on they own roots too, but very slow growing.
Stems: Fan-shaped, lemon to golden yellow, forming with time brain-like mounds to 30 cm in diameter and height.
Ribs: Broad at base, obtuse, rounded, with a deep horizontal depression above the areole.
Areoles: Whitish, close set.
Spines: Often wanting, when present few (3 to 7), unequal only few millimetres long, dark yellow to light brown. Spines are located at the nodes which are spaced evenly (approximately 1-2 cm apart) along the ribs.
Flowers: Very large, white, night blooming and remaining open for the following day, fragrant, up to 22 cm in diameter.
Blooming time: July.

Notes: Variegation, Albinism & Schizochromism.
Variegation: A variegated plant has sectors, patches or stripes with two or more different colours, even distinct shades of green. Plants with variegated stems or leaves are often attractive and highly prized. In most species the stems or leaves are normally green, and variegated epidermis is an uncommon mutation, termed a chimera. A chimeral variegation is due to losing the ability to produce chlorophyll in some of the plant’s tissue, so that this tissue is no longer green. Tissues lacking chlorophyll are usually white or pale yellow coloured (due to carotenoid pigments) or red (due to betalain or anthocyanin pigments) contrasting with the normal green tissue. There are several forms of variegation, depending on the tissues that have been affected. The variegation in some forms is unstable. The extent and nature of the variegation can vary, and sometimes the plant will return to the green form. In others it is stable and does not change under normal conditions. Because the variegation is due to the presence of two kinds of plant tissue, propagating the plant must be by a vegetative method of propagation that preserves both types of tissue in relation to each other.
Albinism: Every once in a while a plant exhibits albinism (completely lacking chlorophyll pigment). This means that its tissue is unable to carry out photosynthesis. The result is a completely cream-white yellow or reddish plant. This plant will be weaker than a green plant, and albinism is generally a fatal trait (it can't produce its own food and it's not getting it from anything else). Without chlorophyll, the albino plant has no way to manufacture the food needed for survival and growth to maturity. This implies that these plants cannot survive on their own roots and necessitate being grafted on a normal green plant that provides food. Some of these albino plants are indeed very popular, and sought after by collectors.
Schizochromism: The yellow or red appearance of some plants is more precisely caused by another aberration called "schizochromism". Here, though, the specific green pigment (chlorophyll) is missing: every other pigment is present at normal levels. The dominant green colouration is lost, but the plant will still more than likely have normal other pigments that give the yellow overall appearance of stems and the red colouration of spines.

Bibliography: Major references and further lectures
1) Curt Backeberg “Die Cactaceae: Handbuch der Kakteenkunde.” Volume 3, 1959
2) Ostalaza, C., Cáceres, F. & Roque, J. 2013. Echinopsis pachanoi. In: IUCN 2013. "IUCN Red List of Threatened Species". Version 2013.2. <www.iucnredlist.org>. Downloaded on 29 March 2014.
3) Britton & Rose "The Cactaceae" 4: 273, 1923
4) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
5) James Cullen, Sabina G. Knees, H. Suzanne Cubey "The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass" Cambridge University Press, 11/Aug/2011
6) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
7)Dobkin de Rios, M. “Trichocereus Pachanoi: a Mescaline Cactus Used in Folk Healing in Peru.” Economic Botany 22 (1968): 191–194.
8) Cordy-Collins, A. “Psychoactive Painted Peruvian Plants.” in: Journal of Ethnobiology 2, no. 2 (1982): 144–153.
9) Torres, D., and M. “San Pedro in the Pressure Pot.” Yearbook for Ethnomedicine and the Study of Consciousness 1995, no. 4 (1996): 283–284.
10) Davis, E.W. “Sacred Plants of the San Pedro Cult.” Botanical Museum Leaflets 29, no. 4 (1983): 367–386.
11) Hofmann, A., Ratsch, C., Schultes, R., “Plants of the Gods: Their Sacred, Healing, and Hallucinogenic Powers.” Rochester: Healing Arts Press, 1992.
12) Furst, P.T. “Shamanism, Transformation, and Olmec Art.” In The Olmec World: Ritual and Rulership. Princeton, N.J.: The Art Museum, Princeton University, 1996.
13) Polia, M., and A. Bianchi. “Ethnological Evidences and Cultural Patterns of the Use of Trichocereus Pachanoi Britt. Et Rose Among Peruvian Curanderos.” Integration 1 (1991): 65–70.
14) Ratsch, Christian., “The Encyclopedia of Psychoactive Plants: Ethnopharmacology and its Applications.” Rochester: Park Street Press, 1998.

Cultivation and Propagation: Variegated and albinos cacti are regarded as choice and difficult in cultivation, but despite that many of them are relatively easy to grow. But be aware that they cannot tolerate prolonged exposure to direct sun light (especially during the hottest summer days), so grow them in half-shade or under filtered sun. They are sometime seen as grafted plants, but many grow well on their own roots, too.
On the contrary, the albinos can survive only if grafted on a strong green base.
Use mineral well-permeable substratum with little organic matter (peat, humus). Water sparingly from March till October and keep perfectly dry in winter at temperatures from 5 to 15 degrees centigrade. (In general these plants are more tender and cannot endure freezing temperatures ) In the rest period no high atmospheric humidity!!
Propagation: Plants are often grafted onto column-shaped cacti.