Betula cordifolia mature to about 3–5 cm long and bear winged nutlets about 2–3 mm long. "Betula cordifolia" is found in Atlantic Canada, Quebec, northwestern Ontario, Northern New York State, and New England. It is generally found in northern habitats or high elevations, particularly on moist ground. "Betula cordifolia" and "Betula papyrifera" are very similar species, indeed they were once considered the same species. The primary methods of distinguishing the one from the other include: Since many of these characteristics vary from tree to tree, ideally several of these characteristics should be noted before making a positive identification. It has been suggested
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