Several of the rarest plant species on Stord grow in or by freshwater. Species like Siberian pink cups, northern green rush and creeping pillwort are found here, but are rare otherwise in Norway. They have quite different distributions, and grow only in southwest Norway north to Sunnhordland. If the environment changes, they could disappear forever.
By Lake Ådlandsvatnet one finds these three species in shallow water in some of the coves. The best growing conditions are fine-grained, slightly muddy bottoms without other dense vegetation. They bow under quite easily in the face of competition. With their difficulties in reproducing they are easily crowded out by other species. In the warm dry summers with low water levels their seeds have the best chances of germinating.
Another lake in the same area is Lake Storavatnet. Here, the characteristic common reed grows, a two metre-high grass that is easy to see. The common reed grows abundantly and quite far out into the water. Beaked sedge and water horsetail are two more common swamp plants that grow in a belt along the shores of most of the freshwater lakes in the southern part of Stord.
