Agaricus bitorquis

Older Names
     Agaricus rodmanii

Cortinarius husseyiKey to Gilled Mushrooms     Key
This is a key to gilled mushrooms, that is, mushrooms having a definite cap with a fertile surface consisting of gills. The fruiting body usually also has a stem, although that may be lateral or absent (usually, then, the mushroom is growing from wood). You can use this key to identify mushrooms that you find.

TricholomaAgaricales     Order
Fruiting body containing fibers (usually in the stalk)

Agaricus campestrisAgaricus     Genus
Gills free
Spore print chocolate brown
Annulus almost always present, usually membranous
The gills are usually pink or silvery-grey at first, but are colored chocolate brown at maturity from the developing spores
The cap and stalk are usually some sort of white or greyish brown, but may have fibrils or scales that are darker (like the portobello)
Growing on the ground, wood chips, or other organic debris

Bitorques     Section
No color-changing reactions.
Often fruiting in poor, dry, pebbly soil.
Flesh often very hard (like a carrot).
Annulus is caligate and single-layered

Agaricus bitorquis     (Quélet) Saccardo

Here are the characters that distinguish this species from the others in its group. For its more general characters, see higher up on the page.
If there's just a few words or a microscopic feature here, a more thorough description can be found above.

Agaricus bitorquis


Microscropic Characters


The ring that comes off the stalk at both its top and its bottom gives the species its name.
The semi-underground fruiting is an important feature. In the lawns and muddy stretches of ground where I often find them, the ones that have clearly broken through the surface are the older ones, and may be buggy or moldy; but one can search around them for less precocious individuals that look (at the moment) like almost completely buried white stones