Bark – grayish with interlacing ridges and alternating light and dark layers of inner bark. American elm (Ulmus americana) is a member of the Ulmaceae family, a group that includes 16 genera and ...

However, almost all mature American elm trees have been killed in the last 50 years by Dutch elm disease, which is caused by a fungus, Ophiostoma novo-ulmi, introduced from Asia. Elm bark beetles ...