Remarks on Potamogeton hybrids based on characters of P. x salicifolius Wolfg. from a new locality in Poland

Information on Potamogeton hybrids, their identification, taxonomy, ecology and distribution has not been sufficiently recognised yet. Based on characters of P. x salicifolius (= P. perfoliatus x P. lucens) from a new locality in Poland - the Gatno lake (the Kaszuby Lakeland in NW Poland) - general comments on Potamogeton hybrids identification are introduced. The description of P. x salicifolius morphology from the Gatno lake are presented. Analysis of quantitative morphological characters of these specimens provided new information on variability of this taxon. The distribution map of P. x salicifolius in Poland, the original draft of P. x salicifolius based on specimens from the Gatno lake and the table with comparison of P. x salicifolius and the characters of parental species are also provided.