Flora of water bodies and streams in Saratov region: The history of research and the current status

Water plants and coastal riparian plants are an integral part of the habitat forming component of water ecosystems in Saratov region. This article gives a review of long-term research of flora in many water reservoirs and water streams of the Saratov region. The analysis of literature in its historical aspect showed that the degree of scientific knowledge about water flora in the Saratov region is still insufficient despite multiple research projects conducted at the end of the 20th and beginning of the 21st centuries. At the moment some research is being conducted concerning the inventory and monitoring of flora and plants in the water reservoirs and water streams of the Saratov region. In this work a complete list of water plants and coastal riparian plants is represented. The flora of water vascular plants contains 103 types (including hybrids) of 54 species, 32 plant families and 3 plant divisions. The leading plant families are Potamogetonaceae, Cyperaceae, Typhaceae and Poaceae. The most widespread species are Potamogeton represented by 18 types and 3 hybrids (13 % of all flora). Multi-species are Typha, Carex, Scirpus and Lemna. To identify the proportion of water species in flora of water streams and water reservoirs, the hydrofitness index IHg was used. It showed that the most diverse water flora exist in the Volgograd water reservoir and lakes. In ponds and oxbow lakes coastal plants play an essential role which can be explained by fluctuations in the levels of these water bodies. In water reservoirs and streams of the Saratov region the most highly active ones are Phragmites australis Potamogeton pectinatus, Typha angustifolia, Nuphar lutea, Sparganium erectum. The percentage of active types makes up only 5 % of all water flora. Among registered vascular plants 30 types are included in the Red Book of endangered species of the Saratov region. In the researched flora 9 invasive species were detected, such as Bidens frondosa, Elodea canadensis, Zizania latifolia, Typha laxmannii, Acorus calamus, Hydrilla verticillata, Vallisneria spiralis, Lemna gibba, Lemna minuta.