<i>BATRACHIUM KAUFFMANNII </i>(RANUNCULACEAE) IN WATERWAYS OF THE MIDLAND RUSSIA
The ecological and biological peculiarities, distribution of habitats and the character of vegetative reproduction of <i>Batrachium kauffmannii</i> (Clerc) V. Krecz. were studied in the small rivers and rivulets of the midland Russia during vegetation periods of 2008-2013. Field observations were conducted in stationary and occasionally attended sites of natural habitation of the species. <i>B. kauffmannii</i> is a vegetative annual or perennial plant, it was very susceptible to environmental factors during its development. Synchronization of development rhythm to the climate, hydrological and water regime of a stream, ground type and flow velocity was the adaptation to the life in the intermittent stream. The clumps of <i>B. kauffmannii</i> significantly transformed the direction, decrease flow velocity and vibration of the stream that created favorable environments for growth of other aquatic plant species, protect and was used as substrate by many representatives of aquatic fauna. The vegetative reproduction of <i>B. kauffmannii</i> prevailed in the studied rivers due to the difficulties of seed introduction related to germination features. Vegetatively originated individuals (ramets) developed all over the period of plant ontogeny but with two seasonal maxima. Seasonal replacement of ramets with different structural organization improved the resistance of <i>B. kauffmanii</i> populations to abrupt changing of habitat in the intermittent streams. The revision of herbarium and observations in nature brought us to conclusion that sites of <i>B. kauffmanii</i> habitats in the studied rivers were not numerous. Populations were effected by the permanent anthropogenic impact and required the intent care and protection.