The most widely diffused swampy formation in the whole of the Bay (and in general in the whole of the Delta), is the common reed thicket (Phragmites australis). The thicket is rather ubiquitous, in the sense that it can be found in slightly salty waters (together with halophilic species- i.e. species that prefer salty environments like the Puccinellia palustris, a variety of saltmarsh-grass), in fresh waters (together with fresh water species like the Lythrum salicaria, commonly known as the purple loosestrife), and even in earthy environments (on the shores of embankments). Generally speaking, as the saltiness increases the thicket tends to become monospecific, in other words to be completely dominated by the common reed. When the level of saltiness becomes excessive, the reed is taken over by decidedly more halophilic species like the sea-lavenders (Limonium spp.) and the saltmarsh-grass (Puccinellia palustris). In the DEEPEST SALTY AREAS within the Bay, where the disruption caused by waves and currents is greatest, these is a submerged vegetation.


Fluctuating algae populations of ulva rigida (a variety of green seaweed) and gracilaria verrucosa (a variety of red seaweed) settle on soft, muddy substrata while the gut weed (Enteromorpha compressa) lives on harder (sandy) substrata. The submerged vegetation has few species but reaches enormous quantities of biomass, and in these communities live a large number of planktonic and benthonic animals. Halophilic vegetative groups typical of the delta's habitat grow, in accordance with the specific micro-conditions of the area, AT THE EDGES OF SALTY AREAS where emersion is never prolonged, lime-clay sediments are present, and waves do not cause disturbances. Under regular conditions it is possible to encounter the whole range of typical species by travelling from constantly submerged areas, moving on to areas subject to tidal movements, and ending in areas that are always above water level.
In shallow areas whole prairies settle, dominated by the spiral tasselweed (Ruppia cirrhosa). A variety of glasswort, whose dominant species is the Salicornia annuale (also known as Salicornia veneta) and whose development takes place in the space of just a few months between summer and early autumn, can be found in contact with the spiral tasselweed but in shallower waters. Following this layer is a wetland of sea-lavenders and cordgrasses whose dominant species are the spartina swards and the sea-lavender of the serotinum subspecies. Finally, closer still to the surface of the water, are prairies of saltmarsh-grass (Puccinellia palustris), a Mediterranean species which in Italy can only be found in the lagoons of the Northern Adriatic and which is often found close to the sea aster (Aster tripolium). The saltmarsh-grass prairie is particularly abundant along the Scannone sandbank, where waters are shallow and calm. In lagoon stretches enjoying similar conditions, a dense population of sea club-rush (Bolboschoenus maritimus) settles instead of the saltmarsh-grass. The sea club-rush often grows together with the common reed (Phragmites australis), and can in fact be found at the mouth of the Volano and in the Gorino's northern valleys. Prairies of sea couch (Elymus athericus) and of cordgrass (of the juncea subspecies) settle in even drier and more elevated conditions. The juncea variety of cordgrass is native to the Atlantic coasts of North America and Europe, and has recently settled along our coasts, colonising many sandy areas. Prairies of this plant are common between the beach and the mouth of the Volano, as well as on the Scannone sandbank. Vegetation typical of coastal sandy areas settles on SANDBANKS PERMANENTLY ABOVE WATER, such as can be seen in the outermost part of the Scannone and on the shore of Lido di Volano. When travelling inland from the water's edge, you can find small pioneering plants such as the sea rocket (Cakile maritima), then species typical of the tallest dunes such as the wheatgrass-like Agropyron junceum and the marram grass (Ammophila littoralis). In the INTERNAL AREAS, protected by the sea winds and where the dunes tend to be more consolidated (for example at Goara, Romanina, and on the river's islands), the vegetation evolves into a WOOD. In the more elevated areas furthest from the watertable is a Mediterranean thermophile wood similar to the Mesola Wood, whose main species are sclerophyllous evergreens such as: the holm-oak (Quercus ilex), the Mock Privet (Phillirea angustifolia), the juniper (Juniperus communis), a variety of asparagus of the acutifolius subspecies, and the butcher's broom (Ruscus aculeatus). A mesophyte wood characterised less by Mediterranean and more by continental features settles in less protruding areas, where conditions are cooler and more humid. The dominant species of this wood are: the bay-oak (Quercus robur), the hornbeam (Carpinus orientalis and C. betulus), the hawthorn (Crataegus monogyna), and the privet (Ligustrum vulgare). In the low areas bordering the watertable and in the floodplains not given over to the growing of poplars, there are small hygrophilous woods whose main species are the willow (Salix alba), the white poplar (Populus alba), and the elm (Ulmus minor). Fresh water vegetation grows along the PO OF GORO, in the floodplains, on the embankments, and in the canals. The relatively modest density of the vegetation is due to human pressure exerted on the area: cementing, building embankments, and poplar fields have greatly changed the original landscape. Where human influence has been reduced, thickets of common reed (Phragmites australis) can often be found, as well as populations of floating species such as the duckweed (of the Lemna species), the giant duckweed (Salvinia natans) and the water chestnut (Trapa natam). On the edges, in other words in transition areas between water-based and earth-based habitats, you can find varieties of sedge (Carex elata, C. riparia, C. otrubae), water lilies (Iris pseudoacorus), purple-loosestrifes (Lythrum salicaria), and sometimes summer snowflakes (Leucojum aestivum). Extremely common along the embankments is the false indigo (Amorpha fruticosa), a species native to North America and currently an infesting plant. On some of the dunes placed further back along the Scannone sandbank, rows of tamerisks (Tamarix gallica) and of oleasters (Elaeagnus angustifolia) have been planted and have grown to the point of becoming a wood. These species are non-native plants often used to counter coastal erosion.