# Deadly fibrecap (Inocybe erubescens)

**Inocybe erubescens**

**Known today as.** A pale fibrecap that bruises red, of spring and summer woods.

Kind: Fungus  
Poisoning: Muscarine poisoning (https://thethinkingpress.org/materia-medica/poisons/muscarine)  
Toxic: yes

> **Caution.** Poisonous, and has killed.

## What was it used for?

None.

## What does modern science say?

Its muscarine floods the body: sweating, weeping, salivation, a slowed heart. Atropine, from the deadly nightshade, is the antidote (see [Deadly nightshade](https://thethinkingpress.org/materia-medica/deadly-nightshade)).

## Pharmacognosy and toxicology

- **muscarine**: 

**Mechanism.** Muscarine is a muscarinic agonist that cannot be broken down by the body’s cholinesterase.

**Dose.** It holds a possibly fatal dose of muscarine; atropine is its antidote.

**Standing.** None.

## What lore surrounds it?

Taken for the St. George’s mushroom, which grows at the same season.

The edible mushroom it is mistaken for carries a real tradition of its own: St. George’s mushroom takes its name from fruiting around the saint’s day, 23 April, and has seasonal names across Europe, *Maipilz* in Germany, *marzolino* in Italy; in the Basque Country it is traditionally eaten with snails on the feast of St. Prudentius. None of this belongs to the poisonous fibrecap except as the reason foragers confuse the two.

## Sources

- “*Calocybe gambosa*” (reference article).
- Wikipedia, “Inosperma erubescens,” en.wikipedia.org (read 2 October 2026).
- Wikipedia, “Muscarine,” en.wikipedia.org (read 2 October 2026).
- Wikipedia, “Atropine,” en.wikipedia.org (read 2 October 2026).

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*Deadly fibrecap.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-03. The Thinking Press. https://thethinkingpress.org/materia-medica/deadly-fibrecap

Historical description, not medical advice.