Betula cordifolia that "Betula cordifolia" and "Betula papyrifera" hybridise, however this is unlikely given the more recent evidence of different chromosome numbers. The most conclusive method of identification is from chromosome analysis. Betula cordifolia Betula cordifolia (mountain paper birch, also known as mountain white birch or eastern paper birch) is a birch species native to Eastern Canada and the Northeastern United States. Until recently it was considered a variety of "Betula papyrifera" (paper birch), with which it shares many characteristics, and it was classified as "B. papyrifera" var." cordifolia" (Regel) Fern. "Betula cordifolia" is a deciduous tree that reaches heights of about
Blue-winged warbler Blue-winged warbler The blue-winged warbler ("Vermivora cyanoptera") is a fairly common New World warbler, long and weighing . It breeds in eastern North America in southern Ontario and the eastern United States. Its range is extending northwards, where it is replacing the very closely related golden-winged warbler, "Vermivora chrysoptera". The common name "blue-winged warbler" refers to the bluish-gray color of the wings that contrast with the bright yellow body of the male. The name of the genus "Vermivora" means "worm-eating". The genus used to include nine other new world warblers but now includes only the golden-winged warbler and Bachman's warbler