1. Department of Botany, Kazimierz Wielki University, Ossolińskich 12, 85-093 Bydgoszcz, Poland
2. Polish Academy of Sciences, Institute of Dendrology, Parkowa 5, 62-035 Kórnik, Poland
3. Spanish Research Council (Consejo Superior de Investigaciones Científicas: IBB, CSIC-ICUB). Botanical Institute, Passeig Migdia s/n, 08038 Barcelona, Spain
4. Department of Geography, Montalegre 6, Barcelona University, Spain