Microplastics can not only enter agricultural lands through direct application of plastic materials (for mulching, etc.) but also by means of sewage sludge, composts, etc. From the soil, they easily pass into living organisms, where they can cause disruptions of biological functions, physiological processes, and reproduction, as well as lead to the accumulation of pollutants in biomass and along food chains, inevitably increasing the risk to human health. In this context, it is of great importance to clarify the potentially toxic effects of microplastics on plants, as well possibility of them entering and accumulating in different tissues and organs. The aim of the present study was to assess the potential of wheat and maize to absorb microplastics from the soil through their root systems and the transfer and accumulation of microplastics in underground and aboveground plant organs. Two types of fluorescent plastic particles were used in experiments conducted under controlled conditions, and the different plant organs were observed using a fluorescent microscope. The penetration and accumulation of microplastics from the two studied fractions (27-32 μm and 75-90 μm) was detected in all the organs of the test plants—the roots, stem, and leaves. We established a statistically significant impact of microplastics on the growth and synthesis of biomass in both underground and aboveground organs, with the degree of their impact depending on the type of plant and the size of the plastic particles. Polyethylene microplastics have an effect on the biosynthesis of photosynthetic pigments, and hence on the intensity of the photosynthesis process, with this effect being positive in corn and negative in wheat.