During the reconstruction of vegetation within the archaeological work made by phytolith analysis method certain ratio of the phytolith morphotypes characterizes different plant communities. Short trapezoidal particles are one of the indicators of steppe communities and are specific mostly for the xerophyte graminoids. But these forms are also found in mesophyte grasses. That’s why additional diagnostic information about the role of these particles is needed. Morphometric measurements (length, height, and their ratio) of short trapezoidal morphotypes phytoliths were investigated based on the soil samples taken from the site of real wormwoodfescue strongly degraded steppe, located near the village Poluyamki Mikhailovsky district. The statistical analysis of the data has been carried out. Resizing phytoliths were compared with the data on the occurrence of morphotypes in phytoliths spectra of soil profiles on the investigated area. The study revealed diagnostic (morphometric) features that characterize different degrees of the phytocenoses mesophily. The highest diagnostic value in short trapezoidal graminoid particles are correlation between length and width.