Clitocybe rivulosa

Clitocybe rivulosa, commonly known as the false champignon or fool's funnel, is a poisonous basidiomycete fungus of the large genus Clitocybe. One of several species similar in appearance, it is a small white funnel-shaped toadstool widely found in lawns, meadows and other grassy areas in Europe and North America. Also known as the sweating mushroom, it derives this name from the symptoms of poisoning. It contains potentially deadly levels of muscarine, much higher than the fly agaric (Amanita muscaria) from which the toxin was initially discovered.

Description

A small white or white dusted with buff-coloured mushroom, the 3-4 cm diameter cap is funnel-shaped with decurrent crowded white gills, with specks of pink. The fibrous stipe is up to 4 cm tall and bears no ring. The spore print is white. There is no distinctive taste or smell. It is one of a number of similar poisonous species such as the ivory funnel (C. dealbata) which can be confused with the edible fairy ring champignon (Marasmius oreades), or miller (Clitopilus prunulus).

Taxonomy and naming

It was initially described as Agaricus rivulosus by Christian Hendrik Persoon in 1801, before German naturalist Paul Kummer gave it its current name in 1871.

Distribution and habitat

The false champignon is found in grassy habitats in summer and autumn in Europe and North America, where it can often form fairy rings; individual mushrooms nestled in the grass which often grows richer and greener where they occur. Unfortunately, they often occur in grassy areas where they may be encountered by children or toddlers. This may increase risk of accidental consumption.

Toxicity

The main toxic component of Clitocybe rivulosa is muscarine, and thus the symptoms are those of muscarine poisoning, namely, greatly increased salivation, perspiration (sweating), and lacrimation (tear flow) within 15-30 minutes of ingestion. With large doses, these symptoms may be followed by abdominal pain, severe nausea, diarrhea, blurred vision, and labored breathing. Intoxication generally subsides within two hours. Death is rare, but may result from cardiac or respiratory failure in severe cases. The specific antidote is atropine.