A new locality of Ulva intestinalis was found near Krąplewo in the River Samica Stęszewska located in the Wielkopolski National Park region (Wielkopolska). On the basis of Carlson's index ranges, waters of the Samica Stęszewska river were qualified as eutrophic. In the river single thalluses of U. intestinalis which appeared by its banks were observed. The presence of this Ulva species thalluse...