XVI International Botanical Congess

Ukrainian invasion flora consists of 710 species of vascular plants. According to our data only 80% invasive plant species are capable to naturalize. The distribution only 20 species from them may be considered as the expansion (Amaranthus albus L., Ambrosia artemisiifolia L., Bidens frondosa L., Cenchrus pauciflorus Benth., Echinocystis lobata (Michx.) Torr. et Gray, Grindelia squarrosa (Pursh) Dunal, Iva xanthiifolia Nutt., etc.). That species adapted to new conditions mainly by way increasing of spectrum of habitats, more rarely through the change of phenorhythm. Thirty per cent of that species display polymorphism connected to phenotypical variability (for example, Amaranthus blitoides S.Wats., Ambrosia artemisifolia L.) or hybridization (Helianthus L., Xanthium L.). Thediapason of variability of invasive plants and its role in the plant communities are analyzed.