-The habitats of 356 phytocoenoses dominated by 15 species of aquatic plants were investigated. Among the properties of water, Na + , pH, total Fe, Ca 2+ , NO 3 x , SO 4 2x , hardness and COD-KMnO 4 were the most important in differentiating the habitats of the phytocoenoses studied. Considerable physicochemical differences were found between the waters of the phytocoenoses of Ranunculus circinatus (hard waters rich in Na + ), Nuphar pumila (soft waters with high levels of total Fe), Elodea canadensis, Ceratophyllum demersum (alkaline waters) and Stratiotes aloides (waters containing high concentrations of Ca 2+ and SO 4 2x ). The substrate properties that best differentiated the habitats compared were PO 4 3x , hydration, organic matter content, total N, dissolved SiO 2 , Ca 2+ , Na + and pH. Patches of R. circinatus inhabited substrates containing the highest levels of PO 4 3x . Those of S. aloides were associated with substrates poor in PO 4 3x . Patches of C. demersum were confined to substrates rich in total N. Phytocoenoses of R. circinatus were associated with large lakes, whereas those of N. pumila were restricted mostly to smaller lakes. The deepest parts of lakes were inhabited by Potamogeton lucens. Phytocoenoses of S. aloides occurred mostly in shallow waters, on thick sediments. The investigated phytocoenoses also represent different stages of succession. The phytocoenoses of Potamogeton perfoliatus, R. circinatus, Myriophyllum spicatum and Polygonum amphibium, which develop on mineral substrates, initiate the process of succession, whereas those of Myriophyllum verticillatum, Nymphaea candida, Nymphaea alba, N. pumila and S. aloides, which inhabit highly hydrated organic substrates, are characteristic of the late stages of succession.