The aim of the performed investigations was to determine the relationship between the occurrence of meadow-rush communities, their floristic diversity and degree of synanthropisation and the developed geomorphological forms of the flooded areas of the Warta River valley. In the identified meadow-rush communities classified on the basis of the analysis of about 1500 phytosociological surveys taken with the use of the Braun-Blanquet method, the author assessed the floristic abundance of the identified communities on the basis of the general and mean number of species in a phytosociological survey as well as their floristic diversity and degree of synanthropisation in relation to the distribution of these communities on the area topography. From among the identified geomorphological forms, the largest area in the examined fragment of the valley was taken up by the floodplain, whereas the most common communities found on the flooded terrace were those of the Phragmitetea class. The meadow-rush communities varied with regard to their wealth and diversity depending on the place occupied on the flooded areas of the Warta River valley. Communities occurring on the flooded plain exhibited both the highest number of species (from 23 to 87) and the highest index of floristic diversity (H’ from 1.5 to 3.8). The highest resistance to the anthropo-pressure was observed among the communities of the wettest sites belonging to the Phragmitetea class.