The species of this group of boletes have long been popular as edible fungi, and since they are among the safest boletes for the table, it is important to inventory the group for North America, especially from a modern approach to the anatomical study of the basidiocarp, so that accurate identifications can be made. Since these fungi are notorious for their variability it is pertinent to review the pattern of speciation in the genus as a whole. The present contribution is a step in this direction.