The paper describes the floristic diversity and specifies its use value in terms of feeding preferences of konik polski horses and their consumption of permanent grassland in a section of the Wieprz river valley in Roztocze National Park. The flora assessment was conducted by analyzing 79 phytosociological relevés using the Braun-Blanquet method. The results of phytosociological surveys made it possible to distinguish 7 complexes in the Phragmitetea class, 5 complexes and 1 plant community in the Molinio-Arrhenatheretea class, and 1 complex in the Nardo-Callunetea class. Natural values of the examined associations were described based on the total and average number of species in a phytosociological relevé, the Shannon-Wiener index, and the phytosociological structure of plant communities. The use value of dry weight of the analyzed meadows and pastures was estimated by means of the use value number (UVN) and taking into account the and yield size. The phytocoenoses identified in the meadows in the section of the Wieprz river valley under study exhibited high natural values (H’ = 3.20–4.62). The dry weight yields of the examined communities varied (from 1.32 to 5.37 t ha–1), but their sward usually had poor and very poor use value (UVN = from –0.55 to 5.8). Furthermore, it should be noted that the sward of wet meadows is readily consumed by the grazing animals, which contributes to the improvement of the natural and use value of meadows.