1. Department of Invasion Ecology, Institute of Botany, The Czech Academy of Sciences, Průhonice CZ-252 43, Czech Republic
2. Department of Ecology, Faculty of Science, Charles University in Prague, Viničná 7, Prague CZ-128 44, Czech Republic
3. Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, Prague CZ-128 01, Czech Republic