Steven Pollock and Psilocybe Tampanensis

Psilocybe tampanensis is a very rare psychedelic mushroom in the Strophariaceae family. Originally collected in the wild in a sandy meadow near Tampa, Florida in 1977, the fungus has never again been reported in Florida, but was later collected in Mississippi.

The original Florida specimen was cloned, and descendents remain in wide circulation. The fruit bodies (mushrooms) produced by the fungus are yellowish-brown in color with convex to conic caps up to 2.4 cm (0.9 in) in diameter atop a thin stem up to 6 cm (2.4 in) long.

Psilocybe tampanensis forms psychoactive truffle-like sclerotia that are known and sold under the nickname "philosopher's stones". The fruit bodies and sclerotia are consumed by some for recreational or entheogenic purposes. In nature, sclerotia are produced by the fungus as a form of protection from wildfires and other natural disasters.

The species was described scientifically by Steven H. Pollock and Mexican mycologist and Psilocybe authority Gastón Guzmán in a 1978 Mycotaxon publication. According to Paul Stamets, Pollock skipped a "boring taxonomic conference" near Tampa, Florida to go mushroom hunting, and found a single specimen growing in a sand dune, which he did not recognize.

Pollock later cloned the specimen and produced a pure culture, which remains widely distributed today. The type specimen is kept at the herbarium of the Instituto Politécnico Nacional in Mexico. Guzmán classified P. tampanensis in his section Mexicanae, a grouping of related Psilocybe species characterized primarily by having spores with lengths greater than 8 micrometers.