Located between two parallel ridges, Lake Pratignano originates from the phenomenon of splitting the ridges and is one of the most delicate biotopes in the park, to be approached with the utmost respect. Next to the transformation into a peat bog, it is home to a marsh vegetation within which large baskets of carex are recognized. Where the northern mass rises in small isolated cushions appears the Droserarotundifolia, a carnivorous plant wrecked by glaciations and very rare in the Apennine.