Pholiota squarrosa

Pholiota squarrosa is a distinctive wood-rotting mushroom recognised by its dry, shaggy cap densely covered in dark brown recurved scales over an ochre-yellow to rust-brown ground colour. It fruits in dense clusters at the base of broad-leaved trees and is widely distributed across Europe and North America. It is not edible: it causes gastrointestinal upset in many people, and reactions are notably worse when consumed with alcohol.

History

Pholiota squarrosa was first described by the Danish naturalist Otto Friedrich Müller and later placed in the genus Pholiota by Paul Kummer, giving the accepted authority Pholiota squarrosa (Müll.) Kummer. The genus name Pholiota derives from the Greek pholis, meaning scale, and the epithet squarrosa is Latin for scaly or scurfy, both reflecting the conspicuous recurved scales that cover the cap and stem. Field guides have long flagged it as a species to avoid: although it is common, easily recognised, and aesthetically striking, multiple authors note difficult digestion and recorded cases of poisoning.

Overview

Ecologically, P. squarrosa is a saprotroph and weak parasite that decomposes wood, often entering living trees through wounds and decayed areas; it is a frequent coloniser of mountain ash (rowan) and other broad-leaved trees, fruiting in characteristic tufted clusters at the trunk base in summer and autumn. Key field characters are the dry scaly cap and stem (distinguishing it from the sticky-capped look-alikes Pholiota aurivella and Pholiota adiposa), the broadly adnate rust-brown gills, the rust-brown spore print, and the strong garlic-radish smell. It has no culinary or commercial value and should not be eaten.