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
Northern rough-winged swallow Northern rough-winged swallow The northern rough-winged swallow ("Stelgidopteryx serripennis") is a small, migratory swallow. It is very similar to the southern rough-winged swallow, "Stelgidopteryx ruficollis". The genus name, "Stelgidopteryx", is from Ancient Greek and means "scraper wing" and the species name, "serripennis", is derived from Latin and means "saw feather". In the common name, "rough-winged" refers to the serrated edge feathers on the wing of this bird; this feature would only be apparent when holding this bird. Six subspecies of the northern rough-winged swallow are currently recognized. It has been proposed that another race be recognized, "aphracta", but this is