Longemer Lake is home to aquatic plants protected in Europe. Sphagnum mosses form floating rafts called tremblants (trembling). It is also filled with Pumila water lilies, whose yellow flowers grow underwater before coming out to be pollinated. Perennials, aquatic, and submerged plants also dwell under the surface. The lake of Longemer is consequently under specific attention in order not to turn into a peat bog.