We studied the thermophilous grass Bromus erectusin Central Europe to determine its pattern of populationgenetic structure and genetic diversity, using ISSR-PCR fingerprinting to analyze 200 individuals from 37 popu-lations. We found three genetic groups with a clear geographic structure, based on a Bayesian approach. Thefirst group occurred west and south of the Alps, the second east and north of the Alps, and the third was formedby four genetically depauperated populations in Germany. The populations from Germany formed a subset ofthe Bohemian-Moravian populations, with one private allele. Two differentiation centers, one in the Atlantic-Mediterranean and the second in the Pannonian-Balkan area, were recognized by species distribution modeling.The geographic distribution of the genetic groups coincides with the syntaxonomic split of the Festuco-Brometeaclass into the Festucetalia valesiaceae and Brometalia erecti orders. We found a statistically significant decreasein mean ISSR bands per individual from south to north, and to a lesser extent from the east to west. The for-mer was explained by Holocene long-distance migrations from southern refugia, the latter by the difference inthe gradient of anthropopression. We hypothesize a cryptic northern shelter of the species in Central Europe inthe putative Moravian-Bohemian refugium.