The new locality of Salvinia natans (L.) All., confined to oxbow lake, has been identified. It is located at the initial stage of isolation from the main channel of the Khopyor river. S. natans is part of the yellow pod community. Some features of the structure and habitation of this plant in the conditions of the Khopyor river region are indicated. The dependence of the distribution of the species on the territory of the Oka-Don Plain on the hydrological, meteorological and ecological factors is shown. The cur-rent trends in the expansion of the range of the species are considered from the standpoint of its biology and ecology. The expansion of the distribution boundaries of the S. natans in the territory of the Oka-Don Plain is considered as the consequence of climatic changes at the global and regional levels. This species can be considered of the indicator of the features of the structural organization and the state of natural vegetation in the Khoper River basin.
S. natans can also be considered as the bioindicator of the landscape changes and meteorological shifts. Moreover, this is characteristic of the Oka-Don Plain and the whole territory of the East European Plain.