Never eat a wild mushroom identified only from a website, a book or an app. Have every find checked in person by an expert, such as a mycological society.
Identification
The shaggy ink cap is easy to spot: a tall, narrow, white cap 5–15 cm high, first cylindrical and later bell-shaped, covered with shaggy, upturned brownish scales and a smooth brownish top. The free gills are very crowded, white at first, then pink, then black from the edge upwards. As the spores mature, the cap digests itself from the margin and drips a black ink (deliquescence). The tall white stem is hollow and has a narrow, loose ring that often slips down. The spore print is black.
Only young specimens with white gills are suitable for eating. Once the gills turn pink or black, the mushroom quickly becomes inedible.
Habitat and ecology
Coprinus comatus is a saprotroph of nutrient-rich soils. It is typical of lawns, road verges, parks, field edges, building sites and compost heaps, often appearing in groups or lines after rain. It is widespread in Europe, Asia and North America and has been introduced to other continents. The main season is late summer to late autumn, but it can fruit in spring and in mild winters too. It can accumulate heavy metals from polluted ground, so roadside and urban specimens are not suitable for eating.
Uses and importance
Young shaggy ink caps have a delicate texture and mild flavour and are good in soups, omelettes, sautés and sauces. Because of autodigestion they cannot be stored: they must be cooked within a few hours of picking or they turn to ink, even in the refrigerator. In China the species is cultivated commercially and sold fresh. The species has also been studied in the laboratory for its enzymes and nematode-trapping behaviour.
Cultivation
Shaggy ink cap is cultivated in China and elsewhere on pasteurised substrates based on straw, compost or other farm residues, often with a casing layer, similar to button mushroom cultivation. Colonisation takes place at about 22–28 °C and fruiting at about 16–24 °C with high humidity. Harvest must be done at the young egg-like stage and the crop sold or processed immediately. It can also be grown outdoors in garden beds with compost-rich soil.
Safety and edibility
Coprinus comatus is a good edible when young and cooked, and unlike the common ink cap it is not known to cause reactions with alcohol. It must be eaten fresh, before the gills darken. Do not eat specimens from roadsides, industrial land or treated lawns because of heavy metals and other pollutants. Identification of any wild mushroom must be confirmed in person by an expert, for example at a mycological society or by a trained mushroom adviser. The main look-alike, the common ink cap (Coprinopsis atramentaria), causes a toxic reaction with alcohol.
If you suspect mushroom poisoning, call your local emergency number or poison centre straight away, even before any symptoms appear, and keep the remains of the mushrooms.
Look-alikes
The common ink cap (Coprinopsis atramentaria) has a smooth, grey to grey-brown, egg-shaped cap without shaggy scales and grows in clusters, often near buried wood. It contains coprine: drinking alcohol up to several days after eating it causes flushing, palpitations, nausea and a drop in blood pressure. The magpie ink cap (Coprinopsis picacea) has a black cap with white patches and is considered toxic. Small ink caps such as Coprinellus micaceus are much smaller and grow on wood.
Around the world
The shaggy ink cap is one of the most widespread urban mushrooms in the temperate world and a favourite species for beginners on guided forays, as it is distinctive. Many foragers advise collecting it only away from roads and pollution sources.
