Discinaceae

Spring-fruiting ascomycetes of the order Pezizales — cup fungi, which release spores from microscopic sacs rather than from gills. That places them a long way from the gilled mushrooms most foragers learn first, and it’s why their fruiting bodies look wrong: brain- like, saddle-shaped or lobed, with an irregular chambered or cottony interior.

No family here better illustrates the gap between traditional use and safety.

Gyromitra esculenta is named “the edible one”, and the name is not entirely wrong — it has been eaten across Scandinavia, Finland and Eastern Europe for centuries, and is still sold commercially in Finland under mandatory warning labelling. The traditional preparation is elaborate for a reason: repeated parboiling in large volumes of water, each change discarded, in a well-ventilated space. The toxin is volatile, so the steam coming off the pot is itself hazardous, and poisonings have occurred in people who never ate the mushroom.

The toxin is gyromitrin, which hydrolyses in stomach acid to monomethylhydrazine — the same compound used as a rocket propellant. It inactivates pyridoxal-5-phosphate, the active form of vitamin B6, and without it the brain cannot synthesise GABA. The result is seizures, on a delayed course of six to twelve hours, alongside hepatotoxicity, haemolysis and methaemoglobinaemia. Pyridoxine is the antidote, which is unusual — most mushroom poisonings have none.

Gyromitrin is also a suspected carcinogen, and content varies enough between populations and seasons that a preparation which was safe in one place has killed in another.

The practical hazard is identification. False morels appear in spring alongside the genuinely prized true morels (Morchella), and the two are confused every year. A true morel has a hollow cap, pitted like a honeycomb, joined to the stem at its base and hollow all the way through. A false morel has a wrinkled or brain-like cap that hangs free, and a solid, chambered or cotton-filled interior. Cutting it lengthwise settles it in a second.

Gyromitrin (acetaldehyde N-methyl-N-formylhydrazone) is the defining constituent, and essentially the family’s only pharmacological feature of note. Its breakdown product monomethylhydrazine is the actual toxin, which is why gastric acid is a necessary step in the poisoning and why the delay before symptoms is so long.