Sunday, May 30, 2010

Agaricus campestris (Meadow Mushroom)

This weekend I went to Assateague Island with my family and friends and was excited with the possibility of finding some different species. Apparently the sandy, salty soil and the windy conditions at Assateague are not very friendly to mushrooms and I did not see any there (not even Polypores). After we returned I decided to do my walk around the block to see what was going on around here during my absence and see if any new things were growing on my regular path. To my surprise, I found multiple specimens from at least seven different species (A. muscaria, P. fonisecii, S. rugoso-annulata and four others which I'll blog about). The first one follows below:


Two specimens near each other, growing on grass (one with bite marks on the surface of the pileus)

Pileus diameter - 25-29 mm | 37 mm
Pileus height- 10 mm | 12 mm
Stipe length - 23 mm | 41 mm
Stipe diameter at apex  - 7 mm  | 8 mm
Stipe diameter at middle- 6 mm | 7.7 mm
Stipe diameter at base - 6 mm | 6.7 mm

Pileus - white color, convex, round, unicolorous, margin is plane and entire, cuticle is dull, dry, smooth, glabrous. Smell is not distinctive. No volva. Does not bruise any color.

Hymenium - Gilled. Remnants of partial veil present on hymenium in one.  Gills are close, light brown color with pink hue on first day but turning darker brown on second, narrow, smooth, free.

Stipe - central, almost equal, solid (with little caniculli and wholes on inner part), slightly tapered at base, white/cream color, inserted, glabrous, does not bruise any color, no volva, ring visualized in one of the two specimens (12 mm from hymenium)

Spore print - dark brown

Spores - eliptical and smooth. No apical pore visualized under 400X.

These specimens looks like some sort of Agaricus, most probably A. campestris L. (Meadow mushroom). The important thing here to distinguish it from other members of the Agaricacea family would be the fact that this one does not bruise yellow and that it does not have any distinctive smell (a phenolic smell would suggest A. xanthodermis). A. abruptibulbus and A. arvensis bruise yellow but have an anise-like odor but as the name of the former already suggests, it has an abrupt bulb at the stipe base. If this were the case, this mushroom would be edible and a good. A. campestris is a close relative of the "white button mushroom" (A. bisporus)  that is commercially produced and can be found on all supermarkets around the country.  Last, one should be extra extra careful not to mistake A. campestris with Amanita virosa, which has a sac-like volva at the stalk base, white gills that do not change color and white spores.

I am not brave enough to eat gilled mushrooms yet and therefore would not suggest beginners (like me) trying it.

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