Agaricus
arvensis: The Horse Mushroom
The Horse Mushroom is a stately
and impressive mushroom, recognized by its preference for grassy areas, its cap
colors (pale yellow to whitish, often with pressed-down fibers), its sweetish
smell, and its "cogwheeled" ring. The cap will often bruise yellow if
rubbed, and the flesh will sometimes turn yellowish on exposure to air--but the
flesh in the base of the stem is not yellow, which helps distinguish it from
other species. However, there are at least two genetically, biologically, and
morphologically distinct species passing as "Agaricus arvensis"; see
the comments below for details.
I have no idea why they call it
the "horse mushroom," other than because it often grows in fields,
and sometimes fields have horses in them. Seems kind of lame to me. I think
they should call it the "Make Fun of the Foreigner Mushroom" instead,
since my most memorable experience with the species involves me attempting to
back away from a grill in Finland, where my Finnish girlfriend's Finnish father
had just finished igniting the coals with a Finnish match . . . I backed away
fast, and stumbled over a patch of very large Agaricus arvensis mushrooms. I landed
flat on my American butt, with a little piece of Horse Mushroom on my face, and
received a chorus of raucous laughter from my girlfriend's family. They had
quite a few things to say about the sieniammattimies ("mushroom
expert") and his expertise . . .
Description:
Ecology: Saprobic; growing
alone, scattered, or gregariously in grassy places (lawns, fields, and so on);
summer and fall (also spring in California); widely distributed in North
America.
Cap: 7-20 cm; convex at first,
often with a somewhat flattened center; later broadly convex or flat; dry;
white or pale yellowish when young; developing pressed-down fibers or scales
(especially in dry weather); bruising yellow; the margin often with hanging
partial veil remnants.
Gills: Free from the stem;
crowded; whitish at first, becoming brown (without a pink stage).
Stem: 5-15 cm long; 1-3 cm
thick; equal, or slightly bulbous; smooth, or with scales below the ring;
white; sometimes bruising yellow; with a persistent, large ring that is often
"cogwheeled" on the lower surface.
Flesh: Thick and white
throughout; not changing color when exposed, or yellowing slightly; flesh in
stem base not yellowing.
Odor and Taste: Odor sweet
(reminiscent of anise or almonds) when young and fresh, becoming less
distinctive; taste pleasant.
Chemical Reactions: Cap yellow
with KOH.
Spore Print: Dark brown.
Microscopic Features: Spores
7-9 x 4.5-6 ยต; elliptical; smooth.
CLICK DOWN HERE
