Agaric (from the Greek agarihon, a mushroom), a general name for the species of the genus Agaricus, a group of hymenomycetous fungi (i.e. those fungi which have the hymenium exposed on the surface of the spore case), of which the mushroom (q.v.) is the most familiar example. Like all the other Agaricinae, or genera belonging to the same tribe, Agaricus has its "hymenium," or spore-bearing surface, spread over a series of plate-like gills ("lamellae"), radiating from the stalk underneath the umbrella-like "pileus," or cap. In this genus the gills are membranaceous, have a tendency to split into two plates, are acute at their edges, and are persistent until the whole pileus putrefies. The hymenium passes into the somewhat flocculent interior mass or "trama" of the gill; and the spores fall off their "basidia" or pedicels. As the genus includes nearly a thousand British and over twelve hundred European species, the total number of forms included in it must be very large.