Trees of Wisconsin
Ulmus rubra Muhl.
rubra is similar to Ulmus americana. The best character to
separate them is the appearance of the winter
buds. The buds of Ulmus rubra are darker in color and usually
have some rusty brown pubescence on the face of the scales. Buds of U.
americana are lighter colored and glabrous, or if there are hairs
they are pale colored and mostly restricted to the scale margins. The
leaves are similar between the two species, but U. rubra leaves
tend to be rougher on the upper surface and at least some leaves
are strongly folded upward along the midvein. The fruit lacks the
marginal cilia of the fruits of U. americana.
Ulmus rubra is apparently largely restricted to southern Wisconsin, with a few records north to Lincoln County near the Wisconsin River. It grows in habitats similar to U. americana, but is more likely to also be found in upland sites. In Brown County it is most common on and near the Niagaran escarpment.