Abstract
Betula pendula Roth. leaves were found to contain, beside the flavonoids detected earlier by other researchers, isorhamnetin 3-galactoside, acacetin 7-glucoside, and perhaps scutellarein 7-glycoside and quercetin 3-glycoside-7,4'-dimethyl ether. The investigated specimens of this species can be divided into two groups on the basis of the presence or absence in them of 6-methoxykaempferide. Group I was characterized by larger leaf-blades containing this compound, whereas it was absent in group II with smaller leaves. The composition of the leaf flavonoids of B. obscura Kot. samples was identical with that of the specimens of the above-mentioned small leaved B. pendula.