Psilocybe tampanensis, one mushroom from a Florida meadow

Psilocybe tampanensis is a small, rare psychedelic mushroom from the south-eastern United States, known from one collection in Florida in 1977 and a second site in Mississippi reported in 1996. Almost every philosopher’s stone sold today descends from that first Florida specimen, which was cloned in a laboratory and has been kept alive in culture ever since.

A field outside Tampa, summer 1977

In the summer of 1977 Tampa hosted the Second International Mycological Congress. One of the visitors was Steven Hayden Pollock, a physician from San Antonio who studied psychoactive fungi and travelled with a Winnebago he had fitted out as a laboratory. According to Hamilton Morris’s account in Harper’s Magazine (July 2013), Pollock skipped part of the programme to go collecting with the mycologist Gary Lincoff. In a field on the edge of town, among grazing cattle, he noticed a single mushroom he did not recognise.

Pollock cut a piece of tissue from the stem and placed it on agar in his mobile laboratory. Weeks later, back in Texas, small hard granules appeared in the culture and slowly grew into lumps. Those lumps were sclerotia.

The species was described in 1978 by the Mexican mycologist Gastón Guzmán and Pollock in Mycotaxon 7(2): 373 to 376. The name means “from Tampa”. The type locality lies south-east of Brandon, Florida, in Hillsborough County.

What the mushroom looks like

The fruit body is modest. Based on the original description, as summarised in the Wikipedia article on the species:

• Cap: 1 to 2.4 cm across, convex to conical, smooth, ochre brown to straw brown, paler when dry, with a faint bluish tone at the edge.
• Gills: attached to the stem, brown to dark purple-brown with lighter edges.
• Stem: 2 to 6 cm long and 1 to 2 mm thick, slightly thicker at the base.
• Flesh: whitish to yellowish, turning blue where it is damaged.
• Spore print: purple-brown.

Guzmán placed it in his section Mexicanae and saw it as intermediate in form between Psilocybe mexicana and Psilocybe caerulescens. The Mexican species is the source of most other truffles on sale.

The stones, described in a patent

The best early description of the sclerotia is in a patent. Pollock filed it on 11 July 1979 under the title “Camote plant”, and it was granted on 18 August 1981, six months after his death. The patent describes a variety of P. tampanensis that Pollock found as a sector of a pure culture growing on ryegrass seed in San Antonio. On agar it formed occasional sclerotia “usually less than 5 mm” across. On ryegrass seed the first ones appeared after three weeks to a month, matured in about three months and kept growing for six to eight months if left alone.

The patent gives measurements. One specimen grown for five months weighed 22.5 g fresh and measured 5.4 cm at its longest; after air drying it weighed 7.4 g. A larger one weighed 44.6 g fresh and 8.3 g dried. The inside was creamy white, the rind light yellowish brown, and bruised areas could turn blue, violet or green.

A sclerotium is a survival structure. When conditions are poor, the mycelium knits itself into a dense lump that can wait out drought, cold or fire and later give rise to mushrooms again. It is vegetative: it carries no spores. This is the main biological difference with a true truffle, which is a spore-bearing fruit body.

One lineage, kept in culture

Pollock’s culture spread quickly. From 1979 his company Hidden Creek sold cultivation material by mail, and later growers extended his methods. Paul Stamets grew the sclerotia on rye grass and straw in the 1980s, and the German chemist Jochen Gartz reported development times of 3 to 12 weeks. According to Jonathan Ott, cited in the species article, the strains sold in cultivation kits derive from Pollock’s Florida specimen.

The species is often described as found only once in the wild. There is one later record: in 1996 Guzmán reported it from a sandy meadow in a deciduous forest in Pearl River County, Mississippi, a habitat similar to the Florida site (Tulane Studies in Zoology and Botany 30(2): 69 to 74). What is true is that wild finds remain extremely rare, and that the material in trade comes from culture.

What this means for the truffles on sale

A pack labelled Tampanensis contains cultivated sclerotia sold as this species. They come from a long line of laboratory cultures, and over four decades growers may well have favoured lines that crop well. We found no published genetic comparison between today’s commercial Tampanensis and Pollock’s original culture.

The next chapter explains how a nickname Pollock used for these lumps became the trade name for philosopher’s stones of every kind. For what the stones contain, see strength.