Rumex thyrsiflorus in the Åland Islands, SW Finland
Abstract
Rumex thyrsiflorus has principally an eastern distribution in Europe. The western border of its main distribution area runs from Norway and Denmark to the Netherlands and Germany, Austria and further towards the Balkans. The species has spread as an alien further into western Europe. The majority of the observations in Finland are from the Åland Islands and the southern coastal areas with scattered observations in mid-Finland and very few in the northern part. Whereas most of the observations in the southwestern archipelago areas seem to be of indigenous nature, the bulk of those in the mainland areas are of more or less ruderal character. Several observations are of polemochorous character and R. thyrsiflorus has been regarded as a polemochorous species introduced both by Russian and German troops during the second world war. The finds of R. thyrsiflorus in the Åland Islands are distributed in time during roughly two phases, in the eastern archipelago during the 1930s and in the mainland area of Åland from 2004 onwards. All the finds from the 2000s are in more or less ruderal habitats. As several of them are on roadsides, R. thyrsiflorus has most probably been introduced in Åland, presumably from Sweden, in connection with the improvement of roads.
