A. Twigs smooth, not hairy-coated.
B. Bark of branches not corky-ridged.
American Elm.
BB. Bark of branches corky-ridged.
Winged Elm. Wahoo.
AA. Twigs hairy-coated.
B. Bark of branches corky.
Cork Elm. Rock Elm.
BB. Bark of branches not corky; buds coarsely hairy.
Slippery Elm.