Along the Warta river in the section between Świątniki and Rogalinek there is a large cluster of pedunculate oaks, which are a remnant of broadleaved forests that used to grow in the Warta valley. Currently, about 1,400 oaks grow here, constituting the largest cluster of the trees of this species in Europe. More than 60% of the oaks are protected as natural features of historic importance.
The most famous of them are the three oaks from the palace park in Rogalin, shrouded with legend. They carry the names of the mythical rulers of Slavic countries – Lech, Czech and Rus, and the circumferences of their trunks are 670 to 930 cm. Another oak is named Edward and has the circumference of 620 cm. Despite being under the protection, many of the trees wither because of the great capricorn beetle which feeds on them. It is a very rare specimen of the beetle and is protected as well.