American Elm

(Ulmaceae Ulmus americana)

Adopted in 1947.

The American or White elm,  Ulmaceae Ulmus americana, is the largest species of elm. The American Elm was adopted in 1947.  Due to its graceful form and size, it was an extremely popular urban tree before the spread of Dutch elm disease. Once found mostly in eastern North America, remaining populations of mature American elms are concentrated in the American Midwest and Canadian Prairies. The American Elm often reaches 120 feet or taller.

American elm also known as white elm, water elm, soft elm, or Florida elm, is most notable for its susceptibility to the wilt fungus, Ceratocystis ulmi. Commonly called Dutch elm disease, this wilt has had a tragic impact on American elms. Scores of dead elms in the forests, shelterbelts, and urban areas are testimony to the seriousness of the disease. Because of it, American elms now comprise a smaller percentage of the large diameter trees in mixed forest stands than formerly. Nevertheless, the previously developed silvical concepts remain basically sound.

Description:

• Leaf: Alternate, 3 to 6 inches long, 1 to 3 inches wide; margin coarsely and sharply doubly serrate, base of leaf conspicuously inequilateral; upper surface glabrous or slightly scabrous, paler and downy beneath.
• Flower: Appears March to May before leaf buds open, in fascicles of 3 to 5.
• Fruit: Rounded samaras, 3/8 to 1/2 inch across, deeply notched at apex, hairless except for margin; appears April to May.
• Twig: Slender, glabrous, slightly zigzag, reddish-brown; buds over 1/4 inch long, reddish-brown with darker edged scales, often placed a little to one side of the twig.
• Bark: Dark, ashy-gray, flat-topped ridges separated by diamond-shaped fissures; outer bark when sectioned shows distinct, alternating, buff colored and reddish-brown patches. When young it is often quite spongy.
• Form: In the open, the trunk is usually divided into several large, ascending and arching limbs, ending in a maze of graceful drooping branchlets.