Résumé
Great progress in cytotaxonomic research during the last decades indicated an importance of relationships between mor‐ phological features, geographical distribution of plants, and chromosome counts. This study is aimed to ll the gaps in our knowledge on Bolboschoenus chromosome numbers related to morphological di erentiation of plants and their distribution worldwide. We counted gametophytic chromosome numbers in meiotic phase of plants, collected from localities worldwide during the period 1980–2013, and cultivated in an experimental garden in Průhonice. The chromosome numbers of seven species (Bolboschoenus a nis, B. caldwellii, B. grandispicus, B. medianus, B. novae-angliae, B. robustus and B. schmidii) were counted for the rst time. All the studied Bolboschoenus taxa were divided into groups according to chromosome numbers, which were found to correspond to morphotypes formerly described. We have improved the taxonomic classi ca‐ tion of some species. The relationship between chromosome counts and morphotypes appeared to be identical within some continents, and may indicate parallel evolution within the genus.