Agaricus
Agaricus is a genus well known to the public due to the
cultivated mushroom, Agaricus bisporus. A number of people also
know the meadow mushroom, Agaricus campestris. Beyond these two,
the picture tends to be pretty fuzzy. However, Agaricus is an
abundant genus, remarkably well represented in the western U.S.,
especially the Southeastern U.S., and even in the drier portions of the
midwest. The groups of species are reasonably clear cut with a small
number situated around the cultivated mushroom, another small group
around the meadow mushroom, a fairly large group centered around the
forest inhabiting Agaricus silvicola, another around the
diminutive yellow staining A. semotus, A. purpuellus, &c, another
around the poisonous Agaricus xerocomus and A. placomyces,
another around the horse mushroom, Agaricus arvensis, and finally
the red staining, forest inhabiting Agaricus silvaticus group.
Most of the Agaricus species fit reasonably well into these groups.
However, certain Agaricus species pose problems. Agaricus
pinyonensis and A. chionodermus are two such species and these are
discussed later.