New discovered adventive plants from eastern Slovakia.

In August 2012, a floristic research was carried out in the rail transshipment yards in eastern Slovakia. A special attention was paid to the adventive plants including invasive weeds. During the research, one new species - Euphorbia davidii - and three rare species - Geranium purpureum , G. sibiricum , and Grindelia squarrosa - were recorded for the Slovak flora. All the species were probably introduced through the Eastern migration route. Two of these invasive or potentially invasive species, E. davidii and G. squarrosa , are expected to be spread also in the future. New Slovak localities of all included species are presented in this paper; some data on the European distribution and identification are also provided.