Category Archives: Agaricus arvensis

#02 Agaricus arvensis – Freaky!

Another Horse Mushroom, popped on the same day as Specimen 2010/10/19#01 but in a different spot several miles away.

All features except the crazy scaling on the cap match. Also A. arvensis (in my experience) tends to be rather picky in the rain/temperature conditions in which it’ll grow. Since they popped at the same time as the other specimen, that’s an indicator of their similarity.

The crazy scaling is probably due to the high wind / dry area in which they were growing (think of how a loaf of bread bakes in the oven, the crust hardening and then still soft dough bursting through it to form new crust).

Also, there is some possibility that this might be one of those fuzzy-areas between A. arvensis and A. macrosporus (which grows in conjunction with pines), as these specimens were found growing near oak trees (as you can see the acorns in the images).

Perhaps this is worth a bit more study.

October 25 – The Undentified

Alright, now to go over the mushrooms that I am not 100% certain of:

Agaricus arvensis?Agaricus arvensis?Agaricus arvensis?
Agaricus arvensis?
Agaricus arvensis?

I am at 95% confidence that the above are Agaricus arvensis or the “Horse Mushroom.” However, 95% is not good enough for me to put it in my mouth, chew and swallow. I’ve picked these before and have posted previous specimens here. In fact, in those previous pictures, I believe that there was a tipoff as to its identity. If you look at the 6th one in the set, in the upper left-hand corner of the image you can see the distinctive “cogwheeling” that is present in A. arvensis‘ ring. The cogwheeling isn’t as distinct in these pictures (although I do believe it’s there), so I still hesitate.

Growing in: Lawn.

Cap: 6-7″ in diameter. Convex to flat. Younger buttons pale yellow-buff to white, older specimens white with buff to tan area towards the center. Very fine compressed shag. Flesh, for the most part not bruising to any color except a very very light brown where the cap connects to the stem.

Gills: Free from the stem and crowded. Very pale in the button stage progressing to gray (with very slight hints of pink, but completely desaturated) and finally dark chocolate brown upon maturity.

Stem: Up to an inch thick similar to any other Agaricus stem with a small bulb at the base (more prominent in buttons). Big floppy ring with some cogwheeling.

Spores: Spore print is chocolate brown. Spores smooth and elliptical. Unfortunately my microscope’s calibration is off at the moment so I cannot distinguish exact size.


Unfortunately, these photos do not show the true vivid colors of these mushrooms. They were brilliant red-orange. I’ll add in more info about them here later.

We also came across some funky, slimy yellow mushrooms, but decided against harvesting any samples, as our basket was (at the time) chock-full of edible goodness.

August 26 ’07 – Lot 1

6 unidentified Agaricus?20070826130448_pict0003.jpg20070826130510_pict0004.jpg20070826130538_pict0005.jpg20070826130610_pict0007.jpg20070826130631_pict0008.jpg

Lot of 6 mushrooms found growing in mulch under cedars. The bases were infested with termites (which I found rather odd).

Cap on the largest specimen was 5 inches across. White with what appear to be very small warts (UPDATE: Was just dirt from transport.). Small smattering of light brown here and there. Slightly inrolled margin.

Gills are a pleasant light brown to slightly pinkish brown. Crowded and short, free from stem. Youngest specimen had gray-buff gills and partial veil.

Stem was about 4-5 inches long, white, very prominent floppy ring. Very slightly bulbous at the bottom. Some infested with termites.

Spores dark chocolate brown.

UPDATE: Upon visual comparison of both macro features (cogwheeling on the ring, slight yellow-staining on the cap in pic 5) and spores, this appears to be a specimen of Agaricus arvensis or Agaricus macrosporus.