ECOLOGY OF 2 CYTOTYPES OF BUTOMUS-UMBELLATUS .3. DISTRIBUTION AND HABITAT DIFFERENTIATION IN THE CZECH AND SLOVAK REPUBLICS

The distribution, total frequency of occurrence, regional differences and habitat conditions of diploid and triploid Butomus umbellatus L. w ere studied in the Czech and Slovak Republics.Triploids are more frequ ent than diploids, with numerous localities in warm lowland regions in river floodplains. Diploids were found primarily in the South Bohemia n Trebon basin, outside the warm regions. The two cytotypes do not dif fer in dependence on water depth. Triploids occur more in habitats wit h more alkaline and base-rich soils. Considering the total distributio n of both cytotypes in the area studied, triploid B. umbellatus appear s to be more successful than its diploid progenitor, owing to its wide r habitat range and superiority in vegetative reproduction.