Geum radiatum is a federally endangered high-elevation rock-outcrop endemic herb that is widely recognized as a hexaploid and a relic species. Little is known about G. radiatum genetic diversity, population interactions, or the effect of past augmentations of populations. This study sampled every known population of G. radiatum and used microsatellite markers to measure genetic diversity and population structure. The analysis demonstrates that there is interconnectedness and structure among populations. In addition, the analysis was able to differentiate transplanted individuals and identify putative anthropogenically admixed individuals within augmented populations. Geum radiatum exhibits diversity within and among populations and current gene flow connects the northern populations. This information provides a greater understanding of the genetic sustainability of G. radiatum and what conservation efforts will most help this imperiled species to survive.