Fomes fomentarius

Fomes fomentarius, commonly called the horse’s hoof fungus, is a polypore that grows on several species of dead or dying trees. Its spongy inner layer, amadou, gives the fungus a human history as well as a place in the book’s portrait of mycologist Paul Stamets: fashioned into a hat, it makes his devotion to fungi visible and tangible.

Form and Material

Amadou is the spongy inner layer of Fomes fomentarius. Stamets’s alpine-style hat, which might at first appear to be felt, is made from amadou in Transylvania. The hat is an unusual transformation of fungal matter into clothing: the same organism associated with decaying trees becomes something light enough to wear.

Uses Through History

The amadou layer is flammable and was used in ancient times to start and transport fire. A piece was found in a pouch carried by Ötzi, the five-thousand-year-old Ice Man discovered mummified in an alpine glacier in 1991. Fomes fomentarius also has antimicrobial properties; it was used to dress wounds and preserve food. These uses show the fungus not merely as a tree-dwelling organism but as a practical material people could carry, ignite, and apply.

The Fungus as a Worn Emblem

Stamets often wears his amadou hat onstage, where it makes his immersion in fungi part of his public presence. The narrator describes him as so deeply involved in the fungal world that a fungus is frequently perched on his head. The image becomes literal the next morning in Stamets’s office: he offers the narrator a small pile of amadou hats and invites him to find one that fits. Most are too large, but one sits comfortably; it feels surprisingly soft and almost weightless. Though the narrator feels a little silly wearing a mushroom, he accepts the gift and packs it carefully in his luggage. Fomes fomentarius thus enters the narrative both as a species with a history of useful applications and as an object that carries Stamets’s enthusiasm from his own head into the narrator’s possession.