AbstractMonk's rhubarb,Rumex alpinusL. (R. alpinus), is a perennial plant native to the mountains of Central and Southern Europe. Currently, the distribution ofR. alpinushas been partly affected by its utilization as a vegetable and a medicinal herb. In the mountains of the Czech Republic, it is considered an invasive plant, probably introduced into the Krkonoše Mountains by colonists from the Alps. This study's main aim was to verify whetherR. alpinuswas introduced into the Krkonoše Mountains by alpine colonists or whether it was anthropogenically introduced from the Carpathians. Furthermore, the genetic structure of native and introduced populations ofR. alpinuswas determined. For the evaluation of genetic structure, 417 samples ofR. alpinuswere collected from the Alps, Carpathians, Balkan, Pyrenees, and Czech Mountains. In total, 12 simple sequence repeat (SSR) markers were applied. The results of AMOVA showed a high 60% variation within populations, 27% variation among groups, and 13% among the population within groups. The overall unbiased gene diversity was high (^ĥ= 0.55). The higher level of genetic differentiation among populations (FST = 0.35;p< .01) indicated restricted gene flow between populations. Compared to native populations, limited genetic variability was observed in the nonnative populations. It was concluded that local adaptation, low gene exchange, and genetic drift affected the genetic diversity of nonnativeR. alpinus. The results support a genetic link between Alpine and Czech genotypes ofR. alpinus, while the Carpathians genotypes corresponded to the Balkan genotype.