It was shown that secondary phloem stereome structure has important taxonomic significance. The Ligustrina stereome consisted of sclereids, but Syringa stereome contained fibres. Reasons for this swarming are not known, but no doubt this phenomenon is possible becouse of hydrological structure peculiarity of Norwegian and Greenland seas. Apparently, they were grown out from seeds transported with different cargoes. Thirty-five species were found in several habitats in Beloushia Cuba.
Adventive species grow on man-made and disturbed soils.
Weather variation leaded to strong changes in life span of annual adventive plants. Biennial and perennial plants proved to be less sensitive to the weather variation. Six species, i.e. Deschampsia cespitosa, Taraxacum officinale, Ranunculus acris, R. repens, Barbarea arcuata, Achillea millefolium, have naturalized. They are usual components of secondary communities in different man-made habitats, i.e. road verges, precipices.