Caesar’s mushroom

Statema, B. C. P.

Fungus

Caesar’s mushroom

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
Constituents: ergosterol, organic acids
Qualities: Cold and moist, as Gerard reports Galen holding of all mushrooms. What the degrees mean
In other databases: GBIF search · Wikidata search

Revised October 3, 2026: Checked against its sources, each read in full, in part, or in its abstract. Version 1, first published September 25, 2026.

Caesar’s mushroom: what was it used for?

A favourite of the early Roman emperors.

Caesar’s mushroom: 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 & Toxicology

Constituents

ergosterol ChEMBL
organic acidschiefly 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.

Toxic dose

A food, given correct identification.

Standing

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

Constituent names open the compound’s record at PubChem, and “ChEMBL” beside a name opens its record at ChEMBL, the European Bioinformatics Institute’s database of bioactive molecules. Where a mechanism line was checked against ChEMBL (ChEMBL 37, read 1 October 2026), the check is shown with the measured value and its source paper, or says plainly that nothing has been measured. Doses are as the references give them, for description only; this is not medical advice. Each source carries the result of its check against Crossref, PubMed, or the authority’s page: see Verification.

Caesar’s mushroom: 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.

In Their Own Words

Pliny calls mushrooms a very dainty food, but one deservedly held in disesteem since Agrippina used them to poison her husband, the Emperor Claudius.

“…a very dainty food, it is true, but deservedly held in disesteem since the notorious crime committed by Agrippina, who, through their agency, poisoned her husband, the Emperor Claudius”

Pliny; translated by John Bostock and H. T. Riley, The Natural History of Pliny, Vol. IV, Book XXII, ch. 46, 'Mushrooms' (the translators' note gives the Latin as boleti). Translated, with copious notes and illustrations, by the late John Bostock, M.D., F.R.S., and H. T. Riley, Esq., B.A. London: Henry G. Bohn, York Street, Covent Garden. MDCCCLVI (Project Gutenberg eBook #61113). The text, read in part

Badham says that in ancient Rome the word boletus named the particular mushroom with which, on Agrippina's orders and by Locusta's cookery, Claudius was poisoned.

“…was used in ancient Rome to designate that particular mushroom, which had the honour, under Agrippina’s orders, and Locusta’s cookery, of poisoning Claudius”

Charles David Badham, M.D., A Treatise on the Esculent Funguses of England, Etymologies, p. 7 (and the entry 'Amanita Caesarea, Fries'). London: Reeve, Brothers, King William Street, Strand, 1847 (Internet Archive OCR text). The text, read in part

Each passage is quoted from the text named, which the press fetched and read, and was checked word for word against a fresh copy of it; the link opens that copy. Passages are given as printed, without the editors’ footnote numbers, and with words broken across lines joined.

Sources

Suetonius, Life of Nero. Read in part · the text read
Pliny, Natural History XXII. Read in part · the text read
Wikipedia, “Amanita caesarea,” en.wikipedia.org (read 2 October 2026). Read in full · the text read
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. Read in part · the text read

Verification

Checked

October 1, 2026, and October 3, 2026

Passes

Every sentence read against its sources, in the pass over the remaining 343 entries
The Standing line checked against the authority it names (EMA, WHO, FDA, CITES, Commission E)
Every dated or regulatory claim checked by category across the database
Every source read, in full, in part, or in its abstract, and every sentence checked against what was read (October 3, 2026)

Sources

4 cited: 1 read in full, 3 read in part.

Corrections

None were needed.

What was checked, how, and what was found is set out on the Verification page. A checked source is one whose record was found; it does not make the entry medical advice.

Cite This Entry

Version 1 · first published September 25, 2026 · last revised October 3, 2026

Chicago: “Caesar’s mushroom.” In Materia Medica, edited by B. C. P. Statema. Version 1. The Thinking Press, 2026–. Last modified October 3, 2026. https://thethinkingpress.org/materia-medica/caesars-mushroom.
MLA: “Caesar’s mushroom.” Materia Medica, edited by B. C. P. Statema, version 1, The Thinking Press, 3 Oct. 2026, thethinkingpress.org/materia-medica/caesars-mushroom. Accessed 8 Oct. 2026.
APA: Caesar’s mushroom. (2026, October 3). In B. C. P. Statema (Ed.), Materia medica (Version 1). The Thinking Press. Retrieved October 8, 2026, from https://thethinkingpress.org/materia-medica/caesars-mushroom

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