American
Elm
(Ulmaceae Ulmus americana)
Adopted on March 21, 1941.
The American elm, Ulmaceae Ulmus
americana, was adopted as the
official tree in March 21, 1941 to
commemorate the fact that General George
Washington took command of the
Continental Army beneath one on
Cambridge Common in 1775. It is a large
tree, with gray flaky bark. When growing
in the forest it often attains a height
of 120 feet, but in the open it is
wide-spreading and of lesser height. The
leaves are oval, and dark green, turning
to a clear yellow in the autumn. The
American Elm, like most elms, has been
severely afflicted by Elm Disease.
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.
Taxonomic Hierarchy
|
Kingdom |
Plantae -- Plants |
Subkingdom |
Tracheobionta --
Vascular plants |
Superdivision |
Spermatophyta – Seed
plants |
Division |
Magnoliophyta –
Flowering plants |
Class |
Magnoliopsida –
Dicotyledons |
Subclass |
Hamamelidae – |
Order |
Urticales – |
Family |
Ulmaceae – Elm family |
Genus |
Ulmus L. – elm |
Species |
Ulmus americana L. –
American elm |
Source:
Dendrology at Virginia Tech
U.S. Department of Agriculture
|