Russula brevipes   Peck (1890)   var. acrior  Shaffer (1964)           *All collections: California

In terms of volume Russula brevipes beats all other members of the genus in abundance, particularly in Sierra Nevada. In certain location 80%-90% of the clumps are just this species and that can become frustrating to seekers of more exotic mushrooms. Some years I see it in large volumes on the coast as well. Most fruitbodies, or at least some in a patch develop the turquoise staining that defines var. acrior. Not sure how taxonomically significant this feature is, but the variety has been used for some time now.  It is not clear exactly just how close this species is to its European counterpart Russula chloroides

The turquoise stains define var. acrior.