Conditions and reproduction of lower don populations of Hedysarum grandiflorum Pall. (Fabaceae)

The article presents the results of the monitoring research of Hedysarum grandiflorum Lower Don basin populations (Rostov Region). Eight new populations of the species are revealed in the region, their habitat conditions are described. Quantitative characters of populations studied and coenotic role of H. grandiflorum are lower than it is observed in optimal conditions. In relation to their ontogenetic structure, the populations are normal, mostly incomplete, having right-sided or centered ontogenetic spectrum. According to delta-omega classification, they belong to mature and ripening; according to replacement index, most of them are unstable or rarely perspective. The principal limiting factors in populations observed are an anthropogenic impact, mainly grazing, and partially discordance between climatic conditions of the region and ecologic requirements of the plant species. H. grandiflorum coenopopulations of the Aksay District are characterized by extremely low number and proportion of the viable seeds per fruit because of seed developmental disorder. Actual seed productivity values vary significantly between years that may condition fluctuations of total seed productivity per individual plant and cause an irregular renewal by seed. In years good for seed maturing, seed productivity of H. grandiflorum may be considered satisfactory.