Salvinia natans

The aquatic fern Salvinia natans is the only representative of the genus Salvinia and the family Salviniaceae in R.N. Macedonia. It is an annual floating plant with a thin unbranched or branched stem. The leaves are arranged in vertebra by 3. The two lateral leaves are oval in shape and float on the surface of the water. Their upper side is warty, and the lower is covered with small hairs that trap air bubbles that allow them to float on the surface of the water. The third leaf is immersed in water, and its leaf plate is cut into threaded parts up to 7 cm long and performs the function of a root. The leaves of this water fern can cover the entire surface of open water thus preventing light from penetrating into the deeper layers of the water body. In that way, the development of other aquatic plants is disabled, that reduces the competition. On the other hand, in those places many species of fish find shelter or spawn.   Salvinia natans inhabits standing freshwaters around the world and is found naturally in Africa, Asia, Central Europe and South America. In much of central and eastern Europe, its populations are declining for unknown reasons, and in some localities it is considered extinct. For these reasons, Salvinia natans is listed in Annex I of the Bern Convention. In R.N. Macedonia this species is registered in rice fields, canals and swamps in Pelagonija, Stip, Kocani, Gevgelija, Monospitovsko Blato, Katlanovsko Blato and other places, as well as in the coastal region of Dojran, Ohrid and Prespa Lakes. In NP Ezerani this plant is found in the community of water lentils with millet (Lemno-Spirodelletum polyrhizae subass. Aldrovandetosum). In 2008, the only site of this community was observed near the village of Dolno Perovo, and small fragments of the community were registered in the lowest course of Golema Reka, before its inflow into Lake Prespa.