Agaricus californicus
Agaricus californicus, commonly known as the mock meadow mushroom, or California agaricus, is a species of fungus in the section Xanthodermati of the genus Agaricus.
The mushroom is mildly poisonous, often causing gastrointestinal upset.
Description
The caps are wide, white, sometimes with a grayish-tan center, dry, and either unchanged or yellowing slightly when bruised. The stalk is long and 1–2 wide, perhaps larger at the base. It has a persistent ring. The spores are brown and smooth.The species, like many members of Agaricus section Xanthodermati, displays a yellowing reaction where its flesh has been damaged, although this is not always readily apparent. The cap surface turns yellow in KOH.
Similar species
Agaricus californicus resembles many other Agaricus species, including A. arvensis, A. bisporus, A. campestris, and A. cupreobrunneus, which are edible and thus require careful identification.The yellowing reaction to bruising is more quickly apparent in A. xanthodermus.