Novelties in the vascular plant flora of Norden during 2015-2018.
This paper presents 169 taxa which are new to Sweden (or to Norden), and about the same number subject to other changes (new names, changed status etc.) since the previous update, printed in 2015. Most new taxa are ephemeral casuals; 32 are regarded as resident. Artemisia tanacetifolia, 22 Hieracium species and 2 species of Sorbus s. lat. are very likely indigenous, whereas the following are regarded as established aliens: Stipa tirsa, Houttuynia cordata, Alchemilla stellaris (Finland), Phedimus stoloniferus, Rhododendron canadense, Mertensia sibirica and Hieracium chrysoprasium. Some important name changes are Carex concolor (formerly C. aquatilis subsp. stans), C. × grahamii (formerly C. stenolepis), and C. × saamica (formerly C. rostrata var. borealis). The genus Kobresia has been included into Carex, and Pennisetum into Cenchrus. The genus Sorbus has been split (now six genera in Norden: Aria, Borkhausenia, Hedlundia, Karpatiosorbus, Sorbus and Torminalis), as well as Mimulus (now Erythranthe and Mimulus) and Minuartia (Nordic taxa are now in Cherleria and Sabulina). Major changes in Rosa are introduced, including R. canina and R. dumalis being replaced with six taxa at species level. Two new combinations are made for two endemic apomicts from Gotland, SE Sweden: Hedlundia atrata and H. faohraei (Levin et al.) Karlsson (basionyms: Sorbus atrata and S. faohraei Levin et al., respectively).