Genebanks aim to maximize the preservation, classification, evaluation and distribution of germplasm in their collections to researchers and breeders. The wild is the source of most of the diversity available to genebanks, so diversity in the wild and how to best capture it also deserves study. The ultimate in valuable information from the wild would be the discovery of a large robust population at a single location on public land that is very easy to visit and contains a large proportion of the total genetic diversity detected in the species, which we have termed a “MegaPopulation”. We here report such a population of the wild potato species Solanum fendleri in the USA (also known as S. stoloniferum) on Mount Lemmon at the top of the Santa Catalina mountains near Tucson, Arizona.