Cytologioal investigations within Galium boreale L. showed the occurrence of tetraploids (2n=44) as well as hexaploids (2n=66) in Europe. Comparative morphological studies failed to demonstrate any differences in characters between the two cytotypes. Crosses between the tetraploid and hexaploid were unsuccessful, due to the occurrence of a strong and effective barrier between the two levels of ploidy. From a taxonomical point of view the two cytotypes are considered as to belong to the same taxon.