The invasion and expansion of three North American species of goldenrod (Solidago canadensis L. sensu lato. S. gigantea Ait. and S. graminifolia (L ) Salisb) in Poland

The geographical distributions of three adventive species of North American goldenrods (S. canadensis L. s.l., S. gigantea Ait. and S. graminifolin (L.) Salisb.) throughout Poland are presented. The history of escape, initial establishent and subsequent spread are documented on the basis of almost 1400 herbarium collections and site records of the authors. Of the three species S. gigantea is the most aggressive S. cunadensis has continued to spread vigorously. but S. graminifolia has barely moved beyond its initial area of establishment. The first two species occur essentially throughout Poland. having expanded from centers in southwestern Poland in the decade between 1840 to 1850. Both of these plants are spreading rapidly and producing vigorous populations which thrive in disturbed and semi-disturbed environments and S. gigantea seems to have now attained the capability of invading stabilized habitats and communities. They are in the process of becoming a serious threat to many natural environments and ecosystems in Poland.