Betula populifolia multiple trunks branching off of an old stump. The leaves are 5-7.5 cm long by 4–6 cm wide, alternately arranged, ovate, and tapering to an elongated tip. They are dark green and glabrous above and paler below, with a coarsely serrated margin. The bark is chalky to grayish white with black triangular patches where branch meets trunk. It is most easily confused for the paper birch ("Betula papyrifera") by means of its bark; it is smooth and thin but does not readily exfoliate like paper birch does. The flowers are wind-pollinated catkins 5–8 cm long, the male catkins pendulous and
Betula pendula continues from a lateral bud. The species is monoecious with male and female catkins found in the same tree. Some shoots are long and bear the male catkins at the tip, while others are short and bear female catkins. The immature male catkins are present during the winter but the female catkins develop in the spring, soon after the leaves unfurl. The leaves have short slender stalks and are long, triangular with broad, untoothed, wedge-shaped bases, slender pointed tips and coarsely double-toothed, serrated margins. They are sticky with resin at first but this dries as they age leaving small white