The pileus cuticle is one-layered in a few species ofRussula, but in the others it can be interpreted as composed of two layers—the epicutis uppermost and below this, the subcutis. The basic difference between the two layers is in hyphal orientation. Cell inflation may obscure the orientation in the cuticles of some species. This has given rise to differing interpretations of cuticular structure, especially in regard to the number of nameable layers present, and thus to differing terms for the layers. No Russulas illustrate this better than those of subsectionVirescentinae, of which the two most common North American species,R. crustosa Peck andR. virescens (Schaeffer ex Secretan) Fries, are discussed and described.