This abstract presents the results of screening for allelopathic activity of three pairs “aboriginal-exotic” of comparison species of herbs, including invasive species, systematically related at the level of the genus. It was shown that a 1% leaf extract of Solidago virgaurea and S. canadensis, Pulmonaria obscura and P. saccharata, Veronica serpyllifolia and V. fi liformis had a similar or equal inhibitory eff ect on the germination and growth of test-plant roots in biotests owing to its chemosystematic correlation. Extracts of Solidago and Pulmonaria species slowed down the rate of germination and root growth by 1.5–2 times lower than the control. In the Salidago sp. experiment options the dynamics of the processes developed according to the type of stress-reaction. The absolute rate of root growth at the exponential stage diff ered twice in the Solidago sp. options: 16.8±0.43 and 8.99±0.23 mm/day in native and exotic specie, respectively. The total germination was close to or equal to the control level. In a comparison pair Pulmonaria sp. germination decreased by 58.66 and 43.5%. V. fi liformis extract inhibited germination by 24.4% more than the native species. Extracts 0.05% extracts of Solidago sp. had no eff ect, P. saccharata and V. fi liformis extracts caused the eff ects of hormesis. P. saccharate option produced an – acceleration of the absolute and relative root growth rate of the test-plants by two times, exceeding the total length of the roots by half compared to the control and the native species. In the V. fi liformis option, the rates of germination and root growth was inhibited by 24.7 and 50.2% of the values of the paired species, respectively. The comparative method increases the level of analysis of bioassay data, allows for a deeper study of the specifi cs of test-plants reactions, and allows the evaluation of the modes of action of allelochemics.