Neue Ausbreitungstendenzen von primär als Eisenbahnwanderer aufgetretenen Pflanzenarten im Ruhrgebiet : Die Beispiele Eragrostis minor, Geranium purpureum und Saxifraga tridactylites

General tendencies of dispersal and demographic dynamics of the former nearly exclusive railway migrating plants Eragrostis minor, Geranium purpureum and Saxifraga tridactylites in the Ruhrgebiet (Germany, Northrhine-Westphalia) are pointed out. The first occurrences of the mentioned species were caused by railway migration. Nowadays, there is an additional spreading independent of railways at least partly.