The effect of motor vehicle emission ingredients on the state of assimilative apparatus of decorative ornamental plants is studied in Dnepropetrovsk. The morphometric indices of leaves of studied species are discussed. The changes of the leaves area and their amount on a plant are shown. The damages of assimilative organs and its structure abnormalities are revealed. The negative influence of motor transport emission on forming and growth of leaves was determined. The Aster novі-belgii L. and Tagetes patula L. are resistant, but Begonia×semperflorens hort, Salvia splendens L. and Zinnia elegans Jacq. are sensitive to the influence of emissions.