Poisonous Tricholomas: the tiger tricholoma and other dangerous species

Knights are a rewarding fall family, but this is exactly where one of the trickiest traps for foragers hides. Most knights are edible or conditionally edible, yet a few species are poisonous, and the most dangerous one, the tiger tricholoma, looks like the tasty grey knight. So knowing the “bad relatives” here is vital.

Let's look at which knights are poisonous, which features give them away, and how not to confuse them with edible ones.

Tiger (leopard) tricholoma — the most dangerous

This is the main poisonous knight of our forests.

• Cap large (up to 12 cm), dirty gray or silvery gray, covered with distinct dark scales, arranged in concentric rings — hence the name “tiger”.
• Gills whitish or yellowish, broad, sometimes with droplets along the edge in young mushrooms.
• Stem thick, whitish.
• Smell and taste mealy.

Tiger tricholoma poisoning is severe: violent digestive upset begins within 1–3 hours and can last several days. Deaths are rare, but dehydration is dangerous.

How the tiger tricholoma differs from the edible grey knight

It's most often confused with the tasty grey knight (the “mousey”). Key differences:

• Size: the tiger is large and massive, the grey knight is smaller.
• Cap: the tiger has distinct dark scales; the grey knight has only fine radial streak-like fibers, with no scales.
• Overall impression: the tiger looks “coarse”, the grey knight more delicate.

Safety rule: don't pick a large gray knight with distinct scales at all.

Other knights to avoid

• Ashen knight — with a pointed bump and burning-hot flesh; causes stomach upset.
• Soapy knight — with a soapy smell and flesh that turns red; inedible.
• Sulphur knight — yellow, with an unpleasant gas smell; poisonous.

A general warning sign in knights is an unpleasant chemical or “soapy” smell and a harsh taste.

Key safety rules

• Don't pick unfamiliar large gray knights with scales.
• Smell them: a soapy, gassy or chemical smell is a reason to pass.
• Check the features of the specific species, not the “general look of a knight”. Read about all types of knights in our guide.
• If you suspect poisoning, drink plenty of fluids and seek medical help right away.

Sources

• “Key to the Fungi of Ukraine” (Kyiv, Naukova Dumka publishing house).
• Tricholoma pardinum on GBIF, the global biodiversity database.
• Tricholoma pardinum on MycoBank, the international fungal nomenclature database.
• Tricholoma pardinum on Wikipedia.