My main interest is plant biogeography. Biogeography I define as everything that has to do with the spatial distribution of biological entities. Thus, biogeography may be studied at any taxonomic (including genes), temporal or spatial scale and biogeographic patterns and processes may depend on e.g. gene-flow, dispersal of diaspores (natural or anthropogenic), the distribution of environmental variables such as geology, soil properties and climate, and historic or ongoing changes in the environment.

Since all biogeographic research depend on the accurate identification of the biological entities studied, I have become increasingly involved in purely taxonomic research. Furthermore, I consider knowledge of biogeographic facts and processes as the key to biological conservation and I have accordingly taken active part in many nature conservation projects and issues.

I am editor-in-cheif of Nordic Journal of Botany.

Current projects:

• Taxonomy, biogeography and evolution of the apomictic Hieracium species of Sweden
• The Flora Nordica project, in particular Amaryllidaceae and Iridaceae
• Documentation of ongoing changes in the flora of south Sweden
• Studies in the autecology of individual bryophyte species, in particular their dependence on the chemical composition of their substrate