Potentilla thuringiaca Bernh. ex Link in Germany—A polyploid enigma

Plants in German states Thuringia and Bavaria previously thought to belong to Potentilla thuringiaca belong to at least three different taxa. Most populations in Thuringia and Bavaria are rather uniform and have a ploidy of 2n = 10x. These populations belong to P. thuringiaca as originally described. A lectotype and an epitype are designated for P. thuringiaca. In an isolated range in Eastern Thuringia, we found octoploids (2n = 8x), which are characterized mainly by a higher number of flowering stems. These populations are described as Potentilla saalae T. Gregor & Korsch. Decaploid (2n = 10x) plants from a very small range in the Bavarian Rhoen with more rounded central leaves are probably of independent origin. The relationship of German P. thuringiaca populations to those in the Alps, the Balkans, the Carpathians, and Eastern Europe is unresolved.