Panaeolus foenisecii

Panaeolus foenisecii, commonly called the mower's or haymaker's mushroom, is a small, fragile saprotrophic fungus that fruits scattered to gregariously in lawns, pastures and other grassy places throughout the temperate world, especially after hay harvest. It has a 1-3 cm campanulate to convex cap that is smoky to dull chestnut brown and strongly hygrophanous, fading to tan or grayish as it dries, often with a darker ring-like band along the margin. Its gills become mottled dull brown as the rough, purplish-brown spores ripen unevenly, and the slender brittle stem is pallid and slightly twisted toward the apex. It is not edible and is best regarded as a toxic lawn mushroom rather than a recreational one.

History

The species was first described by Persoon and sanctioned by Elias Magnus Fries, later transferred by Kuhner; the epithet foenisecii is Latin for 'of the haymaker', reflecting its habit of appearing in mown grass after the hay harvest. Because it does not grow on dung, fruits after haying and produces roughened purplish-brown rather than black spores, it has often been segregated into the genus Panaeolina. Its taxonomic history is tangled: it has at various times been placed in Psilocybe, Psathyrella, Panaeolus and Panaeolina, and recent DNA work has placed the genus near the Galeropsidaceae. For much of the 20th century it carried a reputation as a hallucinogenic 'magic mushroom', largely on the basis of Ola'h's mid-century reports describing it as a 'latent' psilocybin producer.

Overview

Modern chemistry has not supported that reputation. Surveys of specimens from eight countries across three continents, and analyses of more than a hundred German collections, repeatedly failed to detect psilocybin, psilocin or baeocystin; respected authors including Stamets and Gartz conclude the species is not active. What it does reliably contain are 5-substituted indoles, namely serotonin and its precursor 5-hydroxytryptophan, both of which are inactive by mouth and can be mistaken for psilocin in older thin-layer tests. The real hazard is gastrointestinal: small amounts eaten raw have been reported poisonous to young children, and the mushroom has poisoned dogs. Ecologically it is a harmless decomposer of grassland litter, but it grows alongside genuinely psilocybin-bearing relatives such as Panaeolus subbalteatus and Panaeolus cinctulus, so it is an easy and potentially dangerous source of misidentification.