Paxillus involutus, the common roll-rim, is a
fungus that is widely distributed across the Northern Hemisphere and has also been unintentionally
introduced to Australia, New Zealand, and South America. The brownish
fruit body grows up to 6 centimetres (2.4 in) high. It has a funnel-shaped
cap up to 12 centimetres (5 in) wide, with a distinctive in-rolled rim and
decurrent gills close to the
stalk. Genetic testing suggests that the fungus may be a
species complex rather than a single species. A common mushroom of
deciduous and
coniferous woods and grassy areas in late summer and autumn,
P. involutus is
symbiotic with the roots of many tree species, reducing the trees' intake of
heavy metals and increasing their resistance to pathogens. Previously considered to be
edible and eaten widely in Eastern and Central Europe, the mushroom has been found to be
dangerously poisonous; the German mycologist
Julius Schäffer died from ingesting it in 1944. It can trigger the immune system to attack
red blood cells with potentially fatal complications, including
acute renal and
respiratory failure. This
P. involutus mushroom was photographed on
Golovec, a hill near
Ljubljana, Slovenia.
Photograph credit: Petar Milošević
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