Betula occidentalis odorless when scraped. The leaves are alternate, ovate to rhombic, long and broad, with a serrated margin and two to six pairs of veins, and a short petiole up to long. The flowers are wind-pollinated catkins long, the male catkins pendulous, the female catkins erect. The fruit is long and broad, composed of numerous tiny winged seeds packed between the catkin bracts. The identity of similar birches in Alaska is disputed; some include them in "B. occidentalis", while others regard them as hybrids between "Betula neoalaskana" and "Betula glandulosa". Some Plateau Indian tribes used water birch to treat pimples 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