Key to the Trees of Wisconsin
| Some authors have included B. cordifolia as a variety of B. paperifera and the distinction between them is not obvious to me in Wisconsin. Individuals with truncate- or cuneate-based leaves presumably are B. papyrifera, but there appears to be a continuous series of individuals with rounded through cordate based leaves. Within populations of mature plants fitting comfortably into B. papyrifera, young plants may produce clearly cordate leaf bases. Also, the difference in the appearance of the mature bark between these two species is not clear. The following key characters are adapted from the Flora of North America, vol 3. |
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