Abstract
Besides the flavonoids detected earlier, the leaves of purebred B. pubescens specimens were found to contain quercetin 3-arabinoside, isorhamnetin 3-galactoside, luteolin 4'-glucoside, isoquercitrin, acacetin 7-glucoside, and perhaps scutellarein 7-glycoside, whereas B. nana exhibited a low content of myricetin 3-galactoside and quercetin 3-arabinoside, and also possibly quercetin 7-rhamnoside. The qualitative composition of the flavonoids of desiccated B. tortuosa leaves seems to point to the validity of the assumption that this birch is of hybrid origin. The set of flavonoids in B. carpatica was almost identical with that in B. tortuosa.