Minuartia smejkalii is an obligate serpentinophyte plant endemic to the Czech Republic. Since the 1960s, the species’ habitat has undergone strong human-mediated fragmentation, resulting in extinction of some populations and dramatic size reduction of the remaining populations. Thus, contrary to the typically stable serpentine habitats, M. smejkalii habitats underwent a recent and severe decline, which can exacerbate the effects of fragmentation on population genetic structure. We examined the genetic structure of all known M.