ИСТИНА

To reveal plant biodiversity is a base for every floristic analysis. The reference flora of a particular region usually develops in intact territories and should be studied first. This native flora is not a static object, it changes in respond to changing of environment conditions, but the rates of such changes are low. Adventive component of flora, i.e. species, living in territories disturbed or even transformed by men, changes more rapidly and so also need to be carefully studied. Our latest studies show that localities of noticeable anthropogenic influence situated deep inside intact territories are the source of numerous floristic findings. Most of the plant species found in such areas are ruderal or synanthropic. However populations of those species stay in the biocenoses for decades after the men gone. Focusing on grass family (Poaceae) it could be said that despite most of the adventive grasses have wide ranges they are often overlooked. Highly transformed territories, for instance, cities also continuously provide new floristic data. The reasons are: various artificial habitats which sometimes have no analogs in local environment; intensive migration of plant species from a far with transport; introduction of alien plant species for economical or recreational purposes. Usually these newly found species originate from warmer and drier regions then native species are. This phenomenon is better visible for cities of moderate climate. Recent findings of subtropical and even tropical grasses in Moscow is a good example for it.