Invasive rhododendrons in Norway

Garden rhododendrons have begun to establish populations through seed set in the wild in Norway. The Arboretum in Bergen has the largest collection of Rhododendron species in Scandinavia, and staff have observed seedling establishments here for nearly 30 years. Now, similar observations have been made within natural sites along the Norwegian coastline. The fear is that this will lead to an invasion pattern similar to that experienced in Great Britain and Ireland. To be able to compare and understand the nature of this threat, we need to analyse the genetic background of the new establishments. The most common invading Rhododendron in Europe has been reported to be a hybrid of Rhododendron ponticum, R. catawbiense and R. maximum. In this project, Rakel Blaalid and Joachim Paul Töpper of the Norsk institutt for naturforskning (NINA) in collaboration with Per Harald Salvesen of UiB are using the living collections within the Arboretum in Bergen as a reference to assess the heritage of the seedling establishments observed at seven sites from Kristiansand to Nord-Møre.