Preslia 92: 137–165, 2020 137 Intraspecific differentiation of Sparganium erectum in the Czech Republic: molecular, genome size and morphometric analysis Vnitrodruhová diferenciace Sparganium erectum v České republice: molekulární a morfometrické analýzy a stanovení velikosti genomu Soňa Píšová1,2 & Tomáš Fér1 1Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 00 Prague, Czech Republic, e-mail:
[email protected]; 2Czech Academy of Sciences, Institute of Botany, CZ-252 43 Průhonice, Czech Republic, e-mail:
[email protected] Píšová S. & Fér T. (2020) Intraspecific differentiation of Sparganium erectum in the Czech Republic: molecular, genome size and morphometric analysis. – Preslia 92: 137–165. Aquatic and wetland plants tend to be very phenotypically plastic, which accounts for the taxo- nomic difficulties in many groups. In the genus Sparganium, which comprises about 14 species, numerous taxa at different ranks are described. The classification of the genus is based on genera- tive characters on the fruit, which are less influenced by the environment than vegetative charac- ters. Nevertheless, the intraspecific division of Sparganium erectum poses problems, especially the existence of several intraspecific taxa along with intermediate individuals. In this study we examined four European subspecies of S. erectum (subsp. erectum, subsp. microcarpum, subsp. neglectum and subsp. oocarpum) from 64 populations in the Czech Republic. A combination of multivariate morphometrics, AFLPs and genome size estimation allowed us to confirm the cur- rent subspecies classification and investigate putative intraspecific hybridization. Four genetic groups with different genome sizes corresponding to the subspecies were found. Morphological characters that were described in previous studies correlated with these genetic groups and thus affirmed the classification.