Mushroom

A mushroom (or toadstool) is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source.

The standard for the name “mushroom” is the cultivated white button mushroom,  Agaricus bisporus; hence the word “mushroom” is most often applied to those fungi (Basidiomycota, Agaricomycetes) that have a stem (stipe), a cap (pileus), and gills (lamellae, sing. lamella) on the underside of the cap.  These gills produce microscopic spores that help the fungus spread across the ground or its occupant surface.