Badania kariologiczne brzozy ojcowskiej i jej potomstwa [Karyological studies on Betula oycoviensis Besser and its progeny]

In the progeny of Betula oycoviensis pollinated with the pollen of Betula oycoviensis three groups were distinguished: oycovlensis type, verrucosa type, and „nova" type (a small dwarf birch). The number of chromosomes determined in the parental specimens and in several descendent plants belonging to the three types was in all cases 2n=28. Besides the number 28 there occurred simultaneously other numbers of chromosomes in the cells of very young leaves of two specimens. This fact should be considered as a phenomenon of mixoploidy