Flora
Situated on the boundary between the Mediterranean and Continental climates of the Peninsular, the Marshes simultaneously shelter plants adapted to different climates; for example in the Ramone Marshlet, on the edges of the Chiusi Woods, still survive the Frogbit (Hydrocharis morsus-ranae) and the Royal Fern (Osmunda regalis), both plants from a warm wet climate, alongside certain mosses (Sphagnum sp.), more adapted to cold climates of the north and which descended as far as the Marshes during the last Ice Age. Only in the Marshlet, and in a few other areas of the Marsh basin, can still be found fair extensions of the Tufted Sedge (Carex elata), locally called "sarello"; this plant of northern origin develops in bushy formations of more than one individual.
Where the immense reed thickets leave space to the free waters, are the "laminas" formed of plants with floating leaves (e.g. the large White and Yellow Water-lilies) which offer one of the last refuges for several highly specialised species: the Southern Bladderwort (Utricularia australis), a floating carnivorous plant, the Fringed Water-lily (Nymphoides peltata), with its beautiful yellow flowers, and the strange, tiny floating fern Salvinia natans, now extremely rare in Tuscany.