The development starts with white willow (Salix alba) that, under good conditions, emerges when the vegetation - free standard sludge banks lay bare. This is when the willow brushwoods, the so-called "renisuri" appear. Through further accretion and ground elevation, white poplars (Populus alba), tamarisks (Tamarix ramosissima) and later, even some species of the hardwood floodplain settle here. On the embankments that extend in the direction of the flowing water, white polar fringes developed as well. The embankments enclosed where broad reed areas appeared.
The repartition of vegetation on the islands was determined by differences of relief created by the dynamics of the Danube and the respective duration and height of the floods. The major part of both islands (about 85-90%) was covered by reed areas appearing as floating reed, the so-called 'plaur'. They were interspersed with grey willows (Salix cinerea), characteristic of plaur formations, as well as with other moisture indicators of the plaur such as the buttercup (Ranunculus lingua), the sorrel (Rumex hydrola pathum), the gypsy-worth (Lycopus europaeus ), the comfrey (Symphytum officinale), the bittersweet nightshade (Solanum dulcamara) and others.
The open lake waters were covered with swimming salvinia (Salvinia natans) and water-lily/milfoil communities (Myriophyllo-Nupharetum) with floating leaf plants such as yellow water-lily (Nuphar luteum), the pondweed ( Potamogeton natans) and floating macro vegetation such as the water milfoil (Myriophyllum verticillatum), the coontail (Creatphyllum submersum) and others. In some places one could also find the common bladderwort (Urticularia vulgaris) characteristic of meso-eutrophic waters.
Eutrophic waters contained the pondweed (Potamogeton pectinatus.)
In shallow, silted-up areas one could find the water soldier (Stratiotes aloides) which together with (Hydrocharis morsus rranae) formed a characteristic community hydrochariti-Stratiootetum, which is frequent in the smaller, temporarily dried-out water courses of the center of islands as well. As regards the swallow reed-covered border areas of the lakes, the plant community sagittario-Spargnietum emersi settled in the sludgy soil in the direction of the open water: the plant community sagittario-Sparginietum emersi with water plantain (Alisma plantago-aquatica), the arrow head (Sagittaria sagittifolia) and bur-reed (sparganium emersum), occasionally interspersed with hydrocharis morsus-ranae and the common duckweed (lemna minor).
On the whole and under natural conditions, the species diversity of water and swamp plant communities reflects eutrophic, in some places even eutrophic-mesotrophic and mesotrophic conditions. This may be deduced from the former existence of Carex pseudocyperus and the buttercup rannuculus lingua characteristic of mesotrophic waters and growing on peaty sites.
As a consequence of mineralization of the water, salinity indicators of humid and moderately dry seasons of the year, f.e. limonium gmelini, Suaeda maritime, Salicornia herbacea and Platago maritime. Humid-moderately moist sites were settled by large stands of small-growing reed (Phragmites australis) and Aster tripolium adapted to sites with high salinity.
On the western side of the island one could observe groups of tamarix ramosissima which had existed thanks to former wood vegetation clearings. On the embankments the wood vegetation mainly consisted of white willows (Salix alba), white poplars (Populus alba), the common olive (Elaeagnus angustifolia), in places also the white mulberry (Morus alba) which sporadically appears in the lower Danube floodplains, wild pear and white elm (Ulmus carpinifolia). Along the borders of the islands one could also find alluvial meadows of Agropyro rumicion alliance, mainly predominated by couch grass (Agropyron repens) and (agrostis stolonifera).
SOURCE : IBIS TOURS BIRD-WATCHING SPECIALISTS