# False morel (Gyromitra esculenta)

**Gyromitra esculenta**

**Known today as.** A brain-like, reddish-brown spring mushroom of conifer woods.

Kind: Fungus  
Poisoning: Gyromitrin poisoning (https://thethinkingpress.org/materia-medica/poisons/gyromitrin)  
Deadly: yes

> **Deadly.** Deadly if not properly prepared, and not safe even then.

## What was it used for?

Eaten after boiling twice in plenty of water in Finland, where it is still sold with a warning required by law; the Finnish Food Authority no longer recommends eating it.

## What does modern science say?

Gyromitrin breaks down into monomethylhydrazine, a component of rocket fuel. The fumes of cooking can poison the cook; the toxin damages the liver, blood, and nerves, and is potentially carcinogenic.

## Pharmacognosy and toxicology

- **gyromitrin**: hydrolysed to monomethylhydrazine

**Mechanism.** Monomethylhydrazine depletes pyridoxine and so the brain’s GABA, and injures the liver.

**Dose.** Gyromitrin content varies between local populations; potentially fatal raw.

**Standing.** Sold with warnings in Finland; forbidden for sale in several countries.

## What lore surrounds it?

The “brain mushroom” divides cooks and toxicologists: a delicacy to some, a poison to others.

## Sources

- Finnish Food Authority, guidance on false morel.
- Wikipedia contributors. “Gyromitra esculenta.” *Wikipedia, The Free Encyclopedia*. en.wikipedia.org/wiki/Gyromitra_esculenta (read 2 October 2026).
- Wikipedia contributors. “Monomethylhydrazine.” *Wikipedia, The Free Encyclopedia*. en.wikipedia.org/wiki/Monomethylhydrazine (read 2 October 2026).
- Finnish Food Authority (2025). Report: Nearly one-fifth of toxin remains in false morels despite boiling recommendation. ruokavirasto.fi (read 2 October 2026).
- Michelot, D., and Toth, B. (1991). *Journal of Applied Toxicology* 11.

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

Historical description, not medical advice.