Morphological variability and vitality of Rindera tetraspis (Boraginaceae) in the South Urals and Western Kazakhstan

Abstract

Population studies of Rindera tetraspis Pall., a rare endemic species of the steppe zone of the European part of Russia and Kazakhstan, were carried out. The study of the habitats of 11 populations in the Orenburg Region and the Republic of Kazakhstan has shown that the species is confined to various variants of calciphyte steppes on chalk substrates or sandstones. In terms of most morphometric indicators, the northern coenopopulation “Rodnichny” is the leader; the minimum values are noted in the coenopopulation “Verkhnechebendinskie Chalk Mountains, northern extremity”. The discriminant analysis has revealed morphostructural differences between individuals from the majority of coenopopulations. In terms of vitality, four coenopopulations are prosperous, seven ones are depressed. The optimal conditions for the species growth are in the northern part of its range, in more favorable climatic conditions in terms of temperature and humidity, mainly on soils of sand origin. When moving southward, a decrease in size parameters of individuals is observed, associated with insufficient moisture, while their morphological diversity increases. The state of R. tetraspis coenopopulations is stable, but the species is not provided with proper protection measures, so further monitoring of its habitats and improvement of conservation measures are necessary.