Floristic diversity is part of the overall biodiversity of the area and is associated with its sustainability. At present, there are several views on the classification of biodiversity due to the rather large number of its forms. The dependence of the species richness of flora on various factors was studied in a number of works. The influence of geographic factors on the species diversity of flora within the Soksky physiographic region of the forest-steppe zone (part of the province of the High Transvolga, Samara Region) is analyzed. In geomorphological terms, this area is a wavy, elevated plain, dissected by deep and wide river valleys. As a result of the correlation-regression analysis, the equation of the dependence of the number of species of flora on the values of the maximum sweep of heights and the area of the survey is obtained. A signifi- cant influence of these factors on the species diversity of the flora is revealed. The considerable influence of the maximum range of heights is explained by the fact that as the given index increases, the diversity of ecological conditions increases as well. As a result, a relatively larger number of ecological niches are formed. For this reason, it becomes possible to inhabit more species in the territory. Thus, this regularity is confirmed at the level of a single physical and geographical region.