Cei is an eutrophic lake situated at the beginning of the homonimous valley on the Mt. Bondone mountain range, with a thriving vegetation of floating and submerged hydrophytes (Myriophyllo-Nupharetum). The lake is surrounded by reed-thickets and some strips of sedge fields, among which the very rare Caricetum appropinquatae; Prà dell' Albi is a marsh situated in a basin near Cei with wet meadows and a vast sedge field (Caricetum elatae). The areas that surround the two basins are home to many calcicole beech-woods (Carici-Fagetum).