Betula cordifolia young bark is shiny brown with pale brown lenticels. The leaves are alternate, ovate, 6–12 cm long, and double-toothed. As the specific epithet suggests, the leaf base is generally cordate (heart-shaped), however this can be misleading as it is occasionally flat or rounded. The leaves are dotted with many resin glands and the buds are ovoid and blunt. The twigs are yellow-brown to dark-brown and are dotted with resin glands and gray lenticels. They lack the hairs found on "Betula papyrifera". The flowers are catkins, with pollen catkins 2–4 cm long and seed catkins 1–2 cm long. The seed catkins
Betula lenta vertical cracks into irregular scaly plates revealing rough dark brown bark patterns. This, however, only occurs in mature, or ancient, trees and these specimens are not often identified by the public as "B. lenta" due to the difference between the tree's smooth young bark (which the public is most familiar with) and the tree's rough, cracked and plated mature bark. The twigs, when scraped, have a strong scent of wintergreen due to methyl salicylate, which is produced in the bark. The leaves are alternate, ovate, long and broad, with a finely serrated margin. The flowers are wind-pollinated catkins long, the