Elm, American or White
Ulmus americana
Ulmaceae - Elm

Description

Leaves: Alternate; simple; oblong-obovate to elliptic; 4" to 6" long, 1" to 3" wide; deciduous; coarsely doubly serrate margin; acuminate apex; dark green and glabrous or slightly rough above; pale and glabrous or somewhat hairy beneath; unequal base; petiole very short.

Twigs/buds: Twigs slender; zigzag; generally glabrous; brown. No terminal bud; lateral buds about 1/4" long, oval, not sharp-pointed, chestnut-brown.

Flowers/fruit: Monoecious. Fruit a samara; about 1/2" long; oval; a flat thin wing around the seed, wing hairy-fringed and notched at tip; seed cavity distinct; ripens in spring.

Bark: Ash-gray but often mixed with black on older trees; divided into flat-topped ridges with diamond-shaped furrows in between; on older trees can become rough and without a definite pattern; a broken piece of outer bark will have alternating light and dark layers.

Wood: Important; sapwood gray to light brown; heartwood light brown to brown; growth rings distinct; ring-porous; rays not distinct to naked eye; used for boxes, crates, furniture, and veneer.

General: Native to most of the eastern half of the U.S. Intermediate shade tolerance. May be insect and/or disease prone, especially when stressed. Rarely should be planted, though limited use in specific situations may be justified.

Landscape Use: Formerly widely planted as a street tree throughout the U.S. and prized for its graceful, vase-like canopy shape and dense shade. Unfortunately, over the last several decades it has been largely wiped out by Dutch elm disease. Surviving trees can be found in Utah, but they probably have escaped the disease by chance rather than true resistance. Risky to plant. Resistant cultivars are occasionally released, but many of these have not been proven resistant long-term, and some are crosses that have no American elm in them. Try lacebark elm instead. Zones 2-9. Various elm hybrids (like Ulmus procera?) are likely to be encountered occasionally in Utah and can be difficult to identify.

Cultivars: 'Independence', 'New Harmony', 'Valley Forge'.

Characteristics

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