Elm

Elms are trees of the genus Ulmus, family Ulmaceae. They have alternate, simple, doubly-serrate leaves, usually with uneven bases. The fruit is a round samara.

The Dutch elm disease, accidentally introduced into the United States, has been devastating to American elms planted in cities. This is a fungal disease that is borne by a vector, the elm-bark beetle. It affects all species of elm native to North America to some degree. Woodland trees are not quite as susceptible to the disease because they usually lack the root-grafting of the urban elms and are somewhat more isolated from each other.

Native species of elm in the eastern United States are:

• Ulmus alata -- winged elm
• Ulmus americana -- American elm
• Ulmus rubra -- slippery elm (or red elm)
• Ulmus serotina -- September elm
• Ulmas thomasii -- rock elm

Non-native elms sometimes planted in the U. S. include:

• Ulmus pumila -- Siberian elm
• Ulmus glabra -- Scotch elm
• Ulmus procera -- English elm

Another important genus in the Ulmaceae is the genus Celtis, or hackberry[?].