The results of studies carried out in agrocenoses and post-agricultural wastelands in the Kałuszy ska Upland mesoregion between 2003 and 2007 are presented in the paper. The investigations were focused on the occurrence, development as well as variability of morphological features of Anthoxanthum aristatum in various habitat conditions. Five populations of Anthoxanthum aristatum developing in a dense rye field, very scattered rye cultivation, overgrown stubblefield, potato cultivation and a several-year-old fallow land were selected for biometric studies. The populations were examined with respect to 10 morphological features. Anthoxanthum aristatum is a common species, spreading over new territories in the area of Kałuszy ska Upland. It was recorded from 74 stations in the mesoregion so far. The analysis of the results of biometric features demonstrated large differences in the morphological structure of species depending on the origin of specimens. The most propagated and fertile individuals were found on post-agricultural wastelands. On average, the highest specimens were characteristic of the population growing in potato cultivation. Significance of differences between Anthoxanthum aristatum populations depending on the station was proved statistically.