: an enlarged complex fleshy fruiting body of a fungus (as most basidiomycetes) that arises from an underground mycelium and consists typically of a stem bearing a spore-bearing structure; especially: one that is edible—compare toadstool
Fleshy spore-bearing structure of certain fungi (seefungus), typically of the phylum Basidiomycota. It arises from the mycelium, which may live hundreds of years or a few months, depending on its food supply. Some species grow cellular strands (hyphae) in all directions, forming a circular mat with a fairy ring of fruiting bodies around the outside. Popularly, mushroom refers to the edible sporophores, while toadstool refers to inedible or poisonous sporophores, but there is no scientific distinction between the two names. Umbrella-shaped sporophores with spore-shedding gills on the undersurface are found chiefly in the agaric family (Agaricaceae). Mushrooms that are cap-shaped and bear spores in an easily detachable layer on the underside of the cap belong to the family Boletaceae. Together the agarics and boletes include most of the forms known as mushrooms. The morels (phylum Ascomycota) are popularly included with the true mushrooms because of their shape and fleshy structure. Since some poisonous mushrooms closely resemble edible ones, mushrooms intended for eating must be accurately identified. Mushroom poisoning can cause nausea, diarrhea, vomiting, cramps, hallucinations, coma, and sometimes death.