New sites for Isoëtes echinospora (Isoëtaceae) in the Pomeranian lakes (NW Poland)

Two hitherto unknown sites for Isoëtes echinospora Durieu have been discovered in the Pomeranian Lakeland (NW Poland) in the lakes Jelenie Duże and Jelenie Małe. These form the seventh and eighth known populations of this species in Poland in two of its southernmost localities in the European Lowland. The water of both lakes is acid with low pH, electrical conductivity and calcium content. The more valuable I. echinospora site is in Lake Jelenie Małe where it is very abundant. A significant feature of both lakes is freedom from human interference, which offers some chance of preserving both populations.