To determine the characteristics of variability of seed reproduction in the Kentucky bluegrass (Poa pratensis), individual seed variability with respect to the composition of endospermal reserve proteins was studied. Comparative analysis of caryopses obtained by self-fertilization and free fertilization of plants I1 (no. 2-4) and I2 (no. 2-4-7) of the wild-type specimen Murmanskii-95 was performed using SDS-PAGE. Using a cytoembryological express method, we demonstrated that facultative stimulation-autonomous apomeiotic apomixis, along with the formation of meiotic megasporocytes, is characteristic of the Kentucky bluegrass. This method made it possible to determine the consequences of meiotic processes in the maternal plant and to reveal the hybrid nature of seed endosperm.