Tracking the expanding distribution of solidago ×niederederi (Asteraceae) in europe and first records from three countries within the carpathian region

Abstract

Besides the well-known negative effects of invasive plant species on autochthonous plant communities, the breakdown of genetic integrity of indigenous species via alien-to-native hybridisation represents an additional direct threat to native flora which should not be underestimated. Our aim was to survey the current distribution of Solidago ×niederederi, a hybrid that has originated through spontaneous hybridisation between the native European S. virgaurea and allochthonous (North American) S. canadensis. Although this hybrid was first recorded at the very end of the 19th century, most occurrences have been reported during the last decades. It is only known to grow in Europe and its current distribution is still not well explored. Based on field research in the Carpathians, we list five new localities of S. ×niederederi, which represent the first records of this hybrid in Slovakia, Hungary, and Romania. The present paper documents existing reports from 409 sites in 17 European countries. We provide a detailed list of all records from the literature, freely available databases and webpages as well as a summary map of S. ×niederederi’s known distribution. In addition, records are analysed regarding a time context and habitat preferences. Finally, we discuss a potential threat that the hybrid could pose to the genetic integrity of the native European populations of the Solidago virgaurea complex.