Technical Abstract: Solanum sect. Petota, the potato and its wild relatives, contains 232 species, according to the latest taxonomic interpretation. The group is distributed from the southwestern United States to southern Chile, with a concentration of diversity in the Andes of Peru and Bolivia. Contemporary authors disagree regarding species boundaries, treatment of infraspecific taxa, species interrelationships, and the extent and evolutionary significance of natural interspecific hybridization. New morphological and molecular studies of these germplasm collections and prior germplasm collections have notably added to our understanding of systematic relationships and genetic diversity of the group. Explicit morphological studies have revealed unexpected synonymy, and it is likely that the group contains fewer than 200 species. Molecular studies have used nuclear genes to address systematic questions of closely related species boundaries, hypotheses of interspecific hybridization, and intrasectional relationships.