Festuca makutrensis (Poaceae) in the flora of the Eastern Europe

Festuca makutrensis is an assumed tetraploid species of F. valesiaca agg. described from West Ukraine. However, its current interpretation seems misleading, as it is mostly based on the protologue and opinions of Russian authors, lacking knowledge of the type material and the locus classicus. Here, we collected robust population samples (20–30 plants per population) of known F. makutrensis populations in Ukraine (including locus classicus) and Eastern Poland, along with morphologically similar hexaploids, F. rupicola and F. trachyphylla (65 populations in total). We conducted measurements on 1553 flowering plants to analyze their morphology and examined 4439 leaves in cross section to observe their anatomy. Additionally, we determined ploidy in a selected subset of 61 plants using flow cytometry. Contrary to existing works, our findings unequivocally demonstrate that F. makutrensis is a hexaploid taxon. It closely resembles F. rupicola, with the only distinguishing feature being the ever-present, well-developed additional sclerenchyma strands on the leaf cross section. These strands can occasionally fuse with other strands and form irregular sclerenchyma rings in some (> 25%) plants within the population. The distribution of F. makutrensis appears to be limited to Northwest Podolia and Zhytomyr Polissia in Ukraine, as well as the Lublin Voivodeship in Eastern Poland. Reported occurrences of this taxon outside these regions are considered doubtful.