Yellow stainer

Statema, B. C. P.

Fungus

Yellow stainer

Agaricus xanthodermus

Known today as: A white field mushroom that bruises chrome yellow at the base and smells of ink or carbolic.
Kind: Fungus
Constituents: phenol, 4,4'-dihydroxyazobenzene
Poisoning: Gastrointestinal irritants
In other databases: GBIF search · Wikidata search

Caution. Poisonous.

Yellow stainer: what was it used for?

None.

Yellow stainer: what does modern science say?

Causes vomiting and cramps in many who eat it, though some people seem unaffected.

Yellow stainer: is it poisonous?

Yes, in some form or dose. Poisonous. Its poisoning is gastrointestinal irritants: Thirty minutes to three hours: the short latency is reassuring, since the deadly syndromes come later. Historical description, not medical advice; in a poisoning, call a poison centre.

Pharmacognosy & Toxicology

Constituents

phenol ChEMBLthe carbolic smell
4,4'-dihydroxyazobenzenethe yellow

Mechanism

Phenol and related compounds irritate the gut; the mushroom is the commonest cause of mushroom poisoning in Britain, since it grows beside the edible field mushrooms it resembles.

Toxic dose

A meal; some people eat it without harm.

Syndrome

Gastrointestinal irritants

Standing

None.

Gill, M., and Strauch, R. J. (1984). “Constituents of Agaricus xanthodermus: the first naturally endogenous azo compound.” Zeitschrift für Naturforschung C 39. Verified against its record · doi:10.1515/znc-1984-11-1203

The abstract of each source, beneath its citation. For Club members. About the Club or sign in.

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.

Yellow stainer: what lore surrounds it?

The field mushroom’s treacherous double.

In Their Own Words

George Massee describes Agaricus xanthodermus as having a skin that yellows when touched and white flesh that turns yellow when broken, with deep yellow flesh at the base of the stem.

“…cuticle becoming yellowish when touched, and the white flesh changing to yellow when broken; g. free, sinuate, pale rose then grey, finally purple-brown; s. cylindrical, stuffed, ring thin, flesh deep yellow at base, rest white”

George Massee, F.L.S., European Fungus Flora: Agaricaceae, Psalliota, Ag. xanthodermus. London: Duckworth & Co., 3 Henrietta Street, W.C., 1902 (Project Gutenberg eBook #33013). 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

Phillips, R. (2006). Mushrooms. Verified against its record · doi:10.5325/j.ctt7v3rx.7

Verification

Checked

October 1, 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

Sources

2 cited: 2 verified against its record. 1 with the abstract on file.

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

Chicago: “Yellow stainer.” In Materia Medica, edited by B. C. P. Statema. Version 1. The Thinking Press, 2026–. Last modified September 25, 2026. https://thethinkingpress.org/materia-medica/yellow-stainer.
MLA: “Yellow stainer.” Materia Medica, edited by B. C. P. Statema, version 1, The Thinking Press, 25 Sept. 2026, thethinkingpress.org/materia-medica/yellow-stainer. Accessed 8 Oct. 2026.
APA: Yellow stainer. (2026, September 25). In B. C. P. Statema (Ed.), Materia medica (Version 1). The Thinking Press. Retrieved October 8, 2026, from https://thethinkingpress.org/materia-medica/yellow-stainer

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