Tiselius' outstanding collection Potamogetones suecici exsiccati is reviewed and re-evaluated from the viewpoint of the present nomenclature and taxonomy. All 150 gatherings issued in this collection are listed and interpreted taxonomically. In a few cases new taxonomic findings are given based on molecular investigation of plant material from the type localities. All new names proposed in this collection are listed and checked for their nomenclatural validity and legitimacy. Lectotypes are designated for 64 valid names and authentic specimens listed for 27 additional invalid designations. Two names (and their types) are of particular importance for contemporary plant taxonomy because these are the correct names for recognized and confirmed Potamogeton hybrids: P. × torssanderi for the triple hybrid P. gramineus × P. lucens × P. perfoliatus and P. × lanceolatifolius for P. gramineus × P. nodosus.