Reed canarygrass (Phalaris arundinacea L.) is native to Europe and North America, being invasive in the latter since the 20th century. No phenotypic differences have been found in plants from each continent; genetic analyses have been controversial—implicating or exonerating forage/ornamental cultivars for spread throughout North America. Within central Europe, particularly the Czech Republic, it is unknown whether wild genotypes and cultivars are genetically and phenotypically similar. The objectives of this study were to compare commercial forage and ornamental cultivars sold within the Czech Republic with wild genotypes from native populations along major Czech rivers and characterize the extent of phenotypic and genetic variation. Several phenotypic traits differentiated among genotypes and populations (initial tiller fresh weight, stem dry weight [DW], whole plant above‐ and belowground DW, total no. of tillers, percent cover, crown area, height, leaf and node number). Genetic markers (inter‐simple sequence repeats [ISSRs]) clearly differentiated ornamental cultivars from wild P. arundinacea. ‘Chrastava’, the Czech forage and biomass cultivar was genetically similar to wild genotypes, which have most of the genetic diversity within, rather than among, populations. Cluster analyses showed ornamental cultivar ramets to be heterogeneous, most likely due to clonal mix up or mutations.

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AimThe response of L. salicaria and P. australis plants originating from a broad latitudinal gradient to mineral nutrient and water supply was studied. We suggest implications for mechanisms possibly underlying the invasiveness of these two plant species.Location A common garden tub experiment was carried out at T r ebo ˜ , Czech Republic (49 ° N 14 ° 47 ′ E, altitude 433 m). MethodsPlants of 30 L. salicaria and 6 P. australis populations originating from a wide geographical area in Europe and in Israel (60 °− 32 ° N latitude, 6 ° W − 20 ° E longitude) were cultivated for one growing season at two water levels and three ( L. salicaria ) or two ( P. australis ) nutrient doses, respectively. At the end of cultivation, basic morphological and growth characteristics were recorded. ResultsThe latitude of the original geographical location was the most significant factor, affecting both the phenology and most of the plant morphological and growth characteristics measured in both plant species, with the characteristics related to plant size being negatively correlated with latitude. The effect of nutrient dose was very strong in both species, while the effect of water level was more pronounced in P. australis than in L. salicaria . Main conclusionsThe results confirmed the existence of a large phenotypic variability in both plant species within their native ranges of occurrence. In both plant species, the latitudinal variation in plant morphological and growth characteristics most probably indicates the differentiation of genotypes adapted to local geographical conditions. The plants of both species originating from all geographical locations tested responded to the respective nutrient treatments in a similar manner. Exceptions were found in growth characteristics related to reproduction in L. salicaria , indicating that better nutrient supply could enhance the reproductive ability of certain genotypes. Based on the results obtained, we suggest implications for mechanisms possibly underlying the invasiveness of the plant species studied.