Bog lakes of Polistovsky Reserve are relatively uniform in the flora and vegetation; one can find here only thickets of spatterdock (Nuphar lutea) and reed (Phragmites australis). No other hydrophytes are registered. In lakelets of a lake-denudation complex one can sometimes find water lily (Nymphaea candida) and spatterdock. Flora and vegetation of the rivers of Polistovsky Reserve are richer. Floristically, the most interesting seems to be lake Polisto. Unfortunately, only its northern part belongs to the Reserve, but this is the part with extensive thickets of clasping-leaved pondweed (Potamogeton perfoliatus), bulrush (Scirpus lacustris), blowout fescue grass (Scolochloa festucacea), rush flower (Butomus umbellatus) can also be found. Even for a short period of observation of the flora of the lake researchers revealed a dynamic change of the mouth of river Osyanka: V.G.Sergienko in 1998 collected northern pondweed (Potamogeton alpinus) and cornstalk weed (P. lucens). Later in 2003, 2004, 2006, despite special searches researchers could not find, though found in 2003, gramineous pondweed in great quantities (P. gramineus L. s.l.); in 2006, its abundance has decreased slightly. The northern lake shore is formed by sand with peat; fluctuations in the level cause continuing shifts of plant groups on the shore, which deserve further study.