The following three species of Fraxinus are frequently misidentified, at least in part due to the mistaken impression created in some popular tree books and perpetuated in introductory classes that the species can be easily distinguished by a single character such as the bark. Fraxinus pennsylvanica is particularly variable and some individuals might be mistaken for either of the other two species below. See the discussions for all three of these species for more information.

The comparisons of fruit described by Voss for Fraxinus in Michigan appear to work well in Wisconsin also and are adopted below.