A comparative analysis of three regional groups of phytocoenoses dominated by Phragmites australis was undertaken in order to find if they reveal any interregional differentiation in the habitat (water and substratum) conditions and if the differences are followed by floristic composition. A group of 60 phytocoenoses studied in mesotrophic and (mostly) eutrophic lakes of midwestern Poland were compared to two groups investigated in moderately nutrient-rich lakes of northeastern Poland (32 phytocoenoses) and nutrient-poor lakes of northern Poland (20 phytocoenoses). Statistical analyses revealed significant habitat differences. Although the groups of phytocoenoses were studied in different regions and different types of water bodies, they occupied habitats poor in bioavailable forms of nutrients in water and organic matter content and sodium in the substratum, which is inconsistent with the general opinion concerning the reed community as indicative for the high trophy level of lakes. Floristic differences among the studied groups of phytocoenoses are not significant in phytocoenotic terms and relate more to the type of lakes than to established habitat differences. This might suggest that the habitat-forming power of Phragmites australis is the main factor to influence habitat properties.