Coprinus comatus

Coprinus comatus, the shaggy ink cap, lawyer's wig, or shaggy mane, is a common fungus often seen growing on lawns, along gravel roads and waste areas. The young fruit bodies first appear as white cylinders emerging from the ground, then the bell-shaped caps open out. The caps are white, and covered with scales—this is the origin of the common names of the fungus. The gills beneath the cap are white, then pink, then turn black and secrete a black liquid filled with spores (hence the "ink cap" name). This mushroom is unusual because it will turn black and dissolve itself in a matter of hours after being picked or depositing spores.
When young it is an excellent edible mushroom provided that it is eaten soon after being collected (it keeps very badly because of the autodigestion of its gills and cap). If long-term storage is desired, microwaving, sauteing or simmering until limp will allow the mushrooms to be stored in a refrigerator for several days or frozen. Also, placing the mushrooms in a glass of ice water will delay the decomposition for a day or two so that one has time to incorporate them into a meal. Processing or icing must be done whether for eating or storage within four to six hours of harvest to prevent undesirable changes to the mushroom. The species is cultivated in China as food.
The mushroom can sometimes be confused with the magpie fungus which is poisonous. In America, the 'vomiter' mushroom "Chlorophyllum molybdites" is responsible for most cases of mushroom poisoning due to its similarity with shaggy mane and other edible mushrooms.
Taxonomy.
The shaggy ink cap was first described by Danish naturalist Otto Friedrich Müller in 1780 as "Agaricus comatus", before being given its current binomial name in 1797 by Christiaan Hendrik Persoon. Its specific name derives from "coma", or "hair", hence "comatus", "hairy" or "shaggy". Other common names include lawyer's wig, and shaggy mane.
"Coprinus comatus" is the type species for the genus "Coprinus". This genus was formerly considered to be a large one with well over 100 species. However, molecular analysis of DNA sequences showed that the former species belonged in two families, the Agaricaceae and the Psathyrellaceae. "Coprinus comatus" is the best known of the true "Coprinus".
Description.
The shaggy ink cap is easily recognizable from its almost cylindrical cap which initially covers most of its stem. The cap is mostly white with shaggy scales, which are more pale brown at the apex. The free gills change rapidly from white to pink, then to black. It is deliquescent. The stipe has a loose ring and measures high by diameter. Microscopically it lacks pleurocystidia. The spore print is black-brown and the spores measure 10–13 by 6.5–8 µm. The flesh is white and the taste mild.
Distribution, habitat and ecology.
It grows in groups in places which are often unexpected, such as green areas in towns. It occurs widely in grasslands and meadows in Europe and North America, from June through to November in the UK. It appears to have been introduced to Australia, New Zealand and Iceland. In Australia the species is sufficiently common to have been featured on a postage stamp issued by Australia Post in 1981.
"Coprinus comatus" is a nematophagous fungus capable of killing and digesting the nematode species "Panagrellus redivivus" and "Meloidogyne arenaria".
Edibility.
The young mushrooms, before the gills start to turn black, are a choice edible mushroom, but should be prepared soon after being collected as the black areas quickly turn bitter. The taste is mild; cooking produces a large quantity of liquid. It can sometimes be used in mushroom soup with parasol mushroom. Large quantities of microwaved-then-frozen shaggy manes can be used as the liquid component of risotto, replacing the usual chicken stock.
"Coprinus comatus" is not to be confused with the common Ink Cap, which contains coprine and can induce coprine poisoning. Symptoms of coprine poisoning include vomiting, diarrhoea, palpitations and a metallic taste in the mouth.
References.
Much of the above article was translated from and Dutch pages.