# Caesar’s mushroom (Amanita caesarea)

**Amanita caesarea*; Latin *boletus**

**Known today as.** An orange-capped amanita of southern Europe’s oak and pine woods, egg-like when young and seated in a white cup.

Kind: Fungus  
Qualities: Cold and moist, as Gerard reports Galen holding of all mushrooms.

## What was it used for?

A favourite of the early Roman emperors.

## What does modern science say?

A highly prized edible, but it resembles the poisonous fly agaric and the death cap, and is safe only when correctly identified.

## Pharmacognosy and toxicology

- **ergosterol**: 
- **organic acids**: chiefly malic and ascorbic acids

**Mechanism.** An edible *Amanita*; the danger is its resemblance to the poisonous fly agaric and the death cap. It also gathers cadmium and lead above the limits set for cultivated mushrooms.

**Dose.** A food, given correct identification.

**Standing.** A highly appreciated edible in Europe, traditionally gathered in Italy.

## What lore surrounds it?

The Romans called it *boletus*. It was in a dish of mushrooms that Claudius was said to have been poisoned, and Nero, his successor, used afterwards to praise mushrooms, the vehicle of the poison, as “the food of the gods.” Claudius had been enrolled among the gods.

## Sources

- Suetonius, *Life of Nero*.
- Pliny, *Natural History* XXII.
- Wikipedia, “Amanita caesarea,” en.wikipedia.org (read 2 October 2026).
- Gerard, J. (1633). *The Herball, or Generall Historie of Plantes*, enlarged by T. Johnson, Book III, “Of Mushromes.” Adam Islip, Joice Norton and Richard Whitakers.

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*Caesar’s mushroom.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-03. The Thinking Press. https://thethinkingpress.org/materia-medica/caesars-mushroom

Historical description, not medical advice.