Abstract
Although overgrowth of naturalized plants would become a major cause of decrease in biodiversity, establishment mechanism of such plants has not been explained. In this study we explored the plant databases of "comparative ecology" and "seed persistence" consist of north European plant species in order to compare ecological traits between species that have been naturalized in Japan and those that have been not. Result of classification tree analysis, indicated that "degree of ruderal" and "seed persistence" have strong association with the possibility of naturalization. The result suggested that foreign plant species with these traits have great potential of naturalization, and that most naturalized plant species in Japan have formed persistent soil seed banks. The latter means that the extermination of such plants is so difficult.
