Leave a mushroom cap on paper overnight and it prints its own fingerprint
Set a sporulating mushroom cap gill-side down overnight and it drops a powdery pattern called a spore print. Its colour, usually white, sometimes brown, black, pink or yellow but almost never blue, green or red, is one of the oldest tools for telling species apart.
A mushroom is the fleshy fruiting body of a fungus, pushed up from an underground network called mycelium to release spores. The benchmark is the cultivated white button mushroom, Agaricus bisporus, so the word usually means a fungus with a stem, a cap and gills underneath. Other shapes get their own names, such as boletes, truffles, puffballs, stinkhorns and morels, and gilled types are often called agarics.
Mushroom and toadstool have never had precise meanings. English writers of the fifteenth and sixteenth centuries spelled the first word many ways, and it may come from the French mousseron, linked to moss. Toadstool appeared in fourteenth-century England, literally a seat for toads, and still suggests something poisonous. In practice the line between edible and toxic species is not neat: a mushroom may be nutritious, poisonous, psychoactive or just unpleasant.
Most mushrooms are basidiomycetes whose spores are shot from microscopic structures on the gills and fall as fine powder, which is why spore prints work. Identification also draws on juices released when the flesh breaks, bruising colours, smell, habitat and season, plus microscopy and chemical tests for some genera. Tasting and sniffing carry real risks from toxins and allergens. Field guides often get you to the genus, but naming a species needs a mature specimen, since buttons lack key features and old ones stop producing spores. Beginners sometimes mistake damp marks on paper for white prints.
Classification has been reshuffled by molecular studies. The classic order is Agaricales, typified by the field mushroom, Agaricus campestris, but not every member produces a mushroom, and many gilled fungi belong to other orders. Chanterelles, for example, sit in the Cantharellales, and milk-caps and russulas in the Russulales.
Source: Mushroom
