Naturalized Saururus. What species are we actually talking about in the Netherlands and Belgium?

A known naturalized population of Saururus in (Flanders) Belgium was included in a molecular study and unexpectedly turned out to be of hybrid origin. This prompted a targeted survey of all known naturalized populations of Saururus in the Netherlands and Belgium. Plant material was analysed using both morphological and molecular methods, and results were compared with herbarium specimens from the native range and with DNA sequences available in GenBank. All naturalized populations proved to be hybrids between Saururus cernuus and S. chinensis, the only two species in the genus. A morphological key is provided to distinguish both parental species and the hybrid.