Environmental preferences of alien aquatic plants observed in Slovakia. Bar plots display the relative occupancy of water bodies according to the origin (artificial, natural) and habitat type (lotic, lentic). Boxplots show the occurrence of alien aquatic plants along environmental gradients of water temperature, conductivity, pH and water depth. Only species with at least 3 environmental measurements are plotted. Boxplots display median (line), interquartile range (box), range (whiskers) and observed values (jittered points). Full names of taxa are presented in Table 1.