Abstract
A comparison of the qualitative composition of leaves from specimens of Polish taxa of the genus Betula L. points to a specific distinction of B. pendula Roth., B. pubescens Ehrh., B. humilis Schrk., B. nana L., and B. oycoviensis Bess., and also B. "nova" which requires description according to the International Code of Botanical Nomenclature. B. obscura Kot. can be recognized only as a subspecies of B. pendula, whereas B. carpatica Waldst. and B. tortuosa Ledeb. may be geographical variaties of one and the same subspecies distinguished within B. pubescens.