Festuca amethystina L. is an interesting species for the analysis of the impact of the profoundness and areal representativeness of the field botanical research on the knowledge about the geographical range of the rare taxa. In the paper the new data on the occurrence of amethyst fescue was presented. These data complete the pattern of the species occurrence in central Poland. The second aim of the article was the analysis of the history of the localities discoveries in the whole country. The development of knowledge on this subject was very uneven. Historical processes influencing the possibility of botany development, and the number of researchers particularly interested in a given taxonomic group or habitat type, were of great importance. The third aim was the assessment if we can conclude about the real geographical range of the species under study from the current knowledge about its occurrence. The results of modelling with the Maxent algorithm were presented. We evaluate the currently known range as realistic, in accordance with the present state of knowledge there is quite a high probability of new localities discoveries, but rather not far from the limits of the known geographical range in the country.