Genetic variability of Eurasian Nuphar species unravels possible routes in which freshwater plants could fill their wide areas

•We studied the history of diversification of Nuphar sect. Nuphar across Eurasia.•We sequenced nuclear ribosomal ITS and chloroplast intergenic spacers.•The section Nuphar originated and diversified in Eastern Asia.•Nuphar pumila and N. lutea spread from the Far East to Siberia and Europe.•Nuphar pumila also migrated from the Russian Far East to North America.