Siah-Keshim Protected Area is situated in the southwest of Anzali wetland (4200 hectares). In this wetland a total of 103 species and sub specific taxa were identified. They belong to 48 families and 78 genera. Among these plants, 5 families are pteridophyta, 29 families are dicotyledones, and 14 families belong to monocotyledones. Geophyte with 44 species (43.1%) is the most frequent life form of the Protected Area. 61.8 percent of species are distributed in different regions, they are considered as cosmopolitan species. The vegetation of Siah-Keshim wetland was studied, using the Braun-Blanquet school. 105 releves in different association individuals were recorded. Phytosociological data were analysed by FCA and HAC methods, using the software Anaphyto. 32 associations were distinguished. They belong to 4 classes, 4 orders and 13 alliances. The following associations constitute the major part of the natural vegetation of the area: Phragmitetum australis, Trapo-Potametum crispi, Sparganietum neglecti, Bidento tripartitae— Polygonetum hydropiperis and Typhetum latjfoliae.
The distribution of plant associations are mainly affected by physical and chemical properties of water, quantity and quality of sediments, depth and intensity of water, as well as, some biological factors.
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