A new locality of endangered bog bulrush Schoenoplectiella mucronata (Cyperaceae) in the Eastern Poland

A new locality of Schoenoplectiella mucronata - an endangered and warm-temperature wetland spe- cies was found in Western Polesie (Eastern Poland). The new station is situated far away to the north-east from all known Polish sites and belongs to the easternmost one within European range of the species. The mesotrophic Lake Kleszczow in which we have found a new population of S. mucronata was characterised by a good ecological state as well as high diversity of aquatic plants dominated by a charophyte meadow. The studied species occurred in a phytocoenosis which is similar to a not known in Poland plant community Typho angustifoliae-Schoenoplectetum mucronati described from Hungary.