Phytodiversity of the Irgiz Floodplain nature monument

The Bolshoy Irgiz River is 375 km long and has a catchment area of 24 thousand km², including the Orenburg Region and the Samara Region. The flora contains 64 species of plants: 14 belong to the class of monocotyledons (Liliopsida) and 48 belong to the class of dicotyledons (Magnoliopsida), the most numerous families by the number of species are Lamiaceae (5), Cyperaceae (5), Potamogetonaceae (5), Polygonaceae (4), Poaceae (4). The ecological spectrum of the flora is represented by hydrophytes (20 species), helophytes (8), hygrohelophytes (5), hygrophytes (19) and mesophytes (12). These are mainly broad-area species of the Eurasian (23), Holarctic (23) and pluriregional (11) ranges. There are only 7 species of plants with narrow range borders. In economic terms the flora consists of 28 species of medicinal plants, as well as forage (23), tanning (15), food (14), dye (13), honey (12), ornamental (11) and poisonous (8) plants. Vegetation is represented by 17 formations and is represented by the coastal-aquatic vegetation type and two subtypes: coastal and aquatic vegetation. The first subtype contains formations: Phragmiteta australis, Typheta angustifolitae, Scirpeta lacustris, Sagittarieta sagittifoliae, Persicarieta amphibii, Alismateta plantago-aquaticae. The second subtype contains: Nymphaeeta candidae, Nuphareta luteae, Potameta lucentis, Potameta perfoliati, Potameta crispus, Lemneta minori, Salvinieta natantis, Hydrocharieta morsus-ranae, Spirodeleta polyrhizi, Lemneta trisulcae, Ceratophylleta demersi. Coastal plant communities are characterized by a 2–3-tier structure, a high degree of projective coverage, and a relatively high abundance of species (from 15 to 26). Water phytocoenoses are poor in species composition, have a spotty character of overgrowth and 1–2 tiered structure. The Irgiz Floodplain nature monument requires compliance with the stipulated protection measures in order to preserve the habitat of rare plant populations – Nuhar luteum L., Nymphaea candida J. et C. Presl., Salvinia natans L. (All.), Cicuta virosa L., Najas major All. Descriptions of phytocenoses were carried out according to the generally accepted method of geobotanical research in the summer of 2018, while tiering, abundance, projective cover and vitality were noted as well as all species included in plant communities were registered.