The pragmatic concept of species in vascular plants

The objective uncertainty of the taxonomic category “species” in vascular plants, associated with the lack of clear thresholds in the degree of feature divergence between populations and the continuity of evolution, allows plant taxonomists to arbitrarily divide populations into “species”. In the minds of many researchers, ideas about the special meaning (sacredness) of the species category and the objective existence of species persist. All this negatively affects both the study of the processes of biodiversity formation and the use of the species category in other fields of fundamental science and applied research. The authors consider convenience for identification and usefulness to be the most important parameters in the separation of species. So, the main criteria to separate species should be usefulness as for botanists and for researches in other sciences. According to our expert estimates, at least 80% of the world’s plant taxonomists use this parameter but, possibly, sometimes unconsciously. The possibility and applicability of other criteria, including reproductive isolation and age of taxa, is discussed.