Betula alleghaniensis colored, peeling bark of yellow birch. For young trees where bark has not yet developed, yellow birch can also be identified by its hairy buds and stems; sweet birch has hairless buds. The yellow birch was first described by François André Michaux in 1812 as "Betula lutea". In 1904, Nathaniel Lord Britton described what he considered to be a new closely related species of birch as "Betula alleghaniensis", differing from "B. lutea" by its shorter fruiting scales and mostly cordate (vs. rarely cordate) leaf bases. After comparing the descriptions and illustrations of "B. lutea" and "B. alleghaniensis", Merritt Fernald found
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