Gastón Guzmán

is a Mexican mycologist and anthropologist. He is considered the world's foremost authority on the genus Psilocybe.
He was born in Xalapa, Veracruz, in 1932. His interest in mycology began in 1955 when as a graduate student he decided to update his school's (National Polytechnic Institute) poorly kept collection of fungi. During his early field work he found a large assortment of species about which little was known at the time. This inspired him to choose fungi as the topic of his professional thesis.
In 1957, after reading R. Gordon Wasson's article "Seeking the Magic Mushroom", he was invited to go on an expedition to study neurotropic fungi in the Huautla de Jimenez region as an assistant to Dr. Rolf Singer. During the last day of the expedition he met R. Gordon Wasson, this chance meeting resulting in a close friendship between the two men for over 25 years.
In 1958, he published his first paper on a blue-staining Psilocybe species and the first paper on the ecology of neurotropic fungi. In 1971, he received a grant from the Guggenheim Foundation of New York, on the recommendation of Richard Evans Schultes to study the genus Psilocybe, which resulted in a comprehensive book on the subject in 1977. Entitled The Genus Psilocybe: A Systematic Revision of the Known Species Including the History, Distribution and Chemistry of the Hallucinogenic Species, it was published in 1983 by J. Cramer of Vaduz. He has since authored eight other books and over 350 papers on Mexican mushrooms and has described more than 200 new taxa of fungi worldwide. More than half of the known psilocybin mushroom species were discovered by Dr. Guzmán.
A cofounder and former president of the Mexican Mycological Society, he has also been president of the Latin American Mycological Association (2000–2002), and is a founding member of the Panamanian Mycological Society. Dr. Guzmán currently holds an emeritus research chair at the Ecological Institute of Xalapa where he founded the Department and Herbarium of Fungi. He is also a guide on "Mexican Mushroom Tours."
His daughter Laura Guzman Davalos is also a prominent mycologist.
The standard author abbreviation Guzmán is used to indicate this individual as the author when citing a botanical name.