KingdomFungiGenusTricholomaSpeciesequestre
Tricholoma equestre
T2 · Organ toxicPublished 2026-10-07Autumn / Winter
The yellow knight was eaten as a good species across Europe for centuries, and then, between 1991 and 2001, a series of cases in France and Poland established that repeated meals cause rhabdomyolysis — the breakdown of skeletal muscle. It is the clearest example in mycology of a hazard that depends on the number of consecutive meals rather than on any single dose.
Block 01 · Record
The problem with 'it has always been eaten'
Paxillus involutus was also eaten for generations and is now T2; Tricholoma equestre is the second and more dramatic case. The pattern is the same in both: a long history of consumption, no acute syndrome to link to the meal, and a harm that appears only when the mushroom is eaten repeatedly over several days. In the French series, patients developed muscle pain, weakness and dark urine two to seven days after three or more consecutive meals, and several progressed to respiratory failure. One patient has died in the published series despite intensive care.
Field characters, and why they are not enough
The cap is 50-120 mm, bright sulphur-yellow to olive-yellow, smooth and slightly viscid, and it carries adhering sand grains because the fruit body grows half-buried in poor sandy soil under pines. The gills are sinuate with a distinct upward notch, bright yellow, close, and the stem has reddish-brown fibrils at the very base. Spores are 6-8 x 4-5 micrometres, ellipsoid, smooth, thin-walled, with a small hilar appendage and no germ pore, and they are inamyloid. Every one of those characters is also true of Tricholoma portentosum, which is harmless — which is precisely the point: there is no field character that separates a safe species from this one.
Habitat and the winter season
The species is ectomycorrhizal with pines on poor sandy soils: dune systems, heathland, pine plantations and the sandy shoulders of forest tracks. It fruits from September through December and, in mild coastal climates, into January, which makes it one of the few large agarics available late in the year — and the reason repeated meals over consecutive weeks are common in the areas where the cases occurred.
What rhabdomyolysis means for the tier
Rhabdomyolysis is the destruction of muscle fibres, releasing myoglobin into the blood; the myoglobin is filtered by the kidney and can cause acute renal failure on top of the muscle damage itself. The tier is T2 rather than T3 because deaths have occurred but are not the typical outcome, and because the harm requires repeated meals rather than any single one. The practical consequence is that 'cooked a small amount once and felt fine' tells you nothing, just as with Paxillus involutus.
Points to carry to the bench
- Bright yellow cap and gills with a sinuate attachment, growing half-buried in sandy pine soil.
- Inamyloid, smooth, thin-walled spores 6-8 micrometres without a germ pore.
- Rhabdomyolysis follows several consecutive meals, not one; latency is two to seven days.
- No field character separates it from the harmless Tricholoma portentosum other than cap colour.
| Cap | shape: Convex to plano-convex, becoming plane with an irregular wavy margin, 50-120 mm across; the margin is inrolled for a long time and often remains slightly downcurved.surface: Bright sulphur-yellow to olive-yellow, smooth, slightly viscid when wet and often carrying adhering sand grains; the centre may develop faint reddish-brown fibrils.margin: Inrolled then irregularly wavy; not striate, and free of veil remnants. |
|---|---|
| Gills | attachment: Sinuate to adnexed, with a distinct upward notch where the gills meet the stem.spacing: Close, 3-4 gills per millimetre, with three to five series of intermediates — the intermediate series are noticeably irregular in length.edge: Entire and concolorous, bright yellow; the gills never show red or brown spots even on old specimens. |
| Spore print | Ellipsoid to broadly ellipsoid, smooth, thin-walled, with a small hilar appendix and no germ pore.Smooth and inamyloid; no oil drop, and the spores collapse irregularly on drying. |
| Habitat and season | Ectomycorrhizal with pines on poor, sandy soils — dune systems, heathland, pine plantations and the sandy shoulders of forest tracks. Fruit bodies are frequently half-buried in sand and are often found only by the disturbance they cause in the surface crust. |
Block 02 · Chemistry
| Reagent | Verdict | Reaction | Weight |
|---|---|---|---|
 MELZ | inamyloid | Spore wall stays pale yellow; no blue-black development at any concentration. | 3.00 |
 FESO4 | negative | Cap flesh unchanged after 60 s. A salmon-pink reaction here would place the specimen in the russulas instead. | 3.00 |
 ANIS | negative | Nothing beyond a faint grey cast on the cap after five minutes; the flesh never darkens, which is what separates it from the strongly reacting tricholomas. | 2.00 |
 KOH5 | negative | Cap cuticle darkens to olive-brown, but the yellow pigments are otherwise stable and produce no red flash. | 2.00 |
 COTTON | acyanophilic | Spores remain unstained; the thin smooth wall shows as a clear outline. | 2.00 |
Injury stain None. The yellow flesh keeps its colour when cut and does not redden, brown or blacken. That absence of reaction matters here: Tricholoma equestre is one of the very few agarics whose harm was discovered only after a long history of consumption, precisely because nothing about the mushroom — including its cut surface — looks wrong.
Block 03 · Confusion
| Separating character | This record | Confused with |
|---|---|---|
| A grey to grey-brown cap with dark radial fibrils over a paler ground, greyish-white gills with a yellow tinge only at the margin, and a mild farinaceous odour; it grows in the same pine stands and is T0. | Tricholoma equestreT2 | Tricholoma portentosum▲ +2 |
| A more intensely golden-yellow species treated as the same hazard; the two were historically separated on cap colour alone and are not reliably distinguishable in the field. | Tricholoma equestreT2 | Tricholoma auratum▲ +0 |
| A bolete with a pore surface rather than gills and a slimy brown cap with a ring; the yellow-olive colour overlaps but the hymenophore does not. | Tricholoma equestreT2 | Suillus luteus▲ +0 |
Toxicity ladder
The toxin reaches an organ and damages it. Latency is the defining hazard: Cortinarius orellanus and Amanita smithiana produce no symptoms for 3 to 20 days, by which time renal function is already falling. T2 also covers syndromes that require a co-factor, such as coprine and ethanol, or a susceptible host, such as Pleurocybella porrigens in dialysis patients.
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