Deadly
False morel
Gyromitra esculenta
The character that does the work
Cut it lengthwise. A true morel is one continuous hollow chamber from cap to stem base. This is stuffed.
Gyromitrin, hydrolysed in the body to monomethylhydrazine
The toxin is volatile, so it partly boils off, which is why the tradition of parboiling exists and why the cook can be poisoned by the steam while the diners are fine. It is also cumulative in effect across meals, so a history of eating it safely means nothing.
Gyromitrin poisoning, in fullThe specimen sheet, in examination order
01Cap
4 to 12 cm, reddish-brown to chestnut, irregularly lobed and folded like a brain or a saddle. Never pitted like a honeycomb.
02Underside
No gills. The fertile surface is the outside of the folds.
03Stem, and the base
Short, pale, often stout and irregularly chambered.
04Flesh, cut
Thin and brittle. Cut lengthwise, the interior is STUFFED with cottony fibre or divided into irregular chambers, never one clean hollow.
05Spore print
White to cream
An ascomycete: it fires spores rather than dropping them, so a print is unreliable and not the test to use here.
How to take one06Where it grows
Sandy soil under conifers, often in disturbed ground and along tracks.
When to look
Typically Mar to Jun in the northern hemisphere. Fruiting swings by weeks with rainfall and by a month or more with latitude, so this is when to look rather than when it will be there.
Northern Europe, northern North America.
What is worth knowing about it
Eaten traditionally in parts of Scandinavia and Eastern Europe after repeated parboiling, which is a tradition of gambling with a volatile carcinogen. Gyromitrin converts in the body to monomethylhydrazine, a compound also used as rocket fuel. The vapour alone has hospitalised people who were only cooking it, and tolerance is not cumulative in the reassuring direction: people who ate it for years have still been poisoned by it.
Confused with
- True morel
This page tells you what to check. It does not tell you the mushroom in your hand is that species, and it cannot. If you are not certain, do not eat it. If you have already eaten something and feel unwell, contact a poison centre and keep an uncooked specimen.
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