American elm (Ulmus americana)
First place champion weeping American elm (Ulmus americana ‘pendula’) in Denver at Regis University.
Species info:
Leaves: Alternate, simple, oblong to obovate, 4"–6" long and 1"–3" wide. Leaf base markedly uneven, margins coarsely doubly serrated. Upper surface dark green and glabrous to slightly rough; underside lighter and softly pubescent.
Leaflets: None (simple leaf).
Leaf Surface: Smooth to slightly rough on top; softer and pale beneath.
Bark: Ash-gray, forming flat-topped ridges separated by diamond-shaped furrows. Broken bark shows alternating light and dark layers—a key ID feature.
Flowers: Inconspicuous; appear before leaves. Produce samaras ~½" long with a thin oval wing, hairy-fringed and notched at the tip.
Fruit: Flat samaras that mature in late spring; dispersed by wind.
Botanical: Ulmus americana
Family: Ulmaceae
Mature Height: 60–80 feet (occasionally over 100 feet in ideal conditions)
Canopy Spread: 40–70 feet; broad and arching
Foliage Type: Deciduous
Tree Shape: Classic vase-shaped crown with high, arching limbs; some cultivars may be more upright, spreading, or pendulous
Growth Rate: Moderate to fast
Flower: Interesting, but not showy
Fruit: Not ornamental
Fall Color: Yellow
Water Use: Moderate; prefers consistent moisture but tolerates periodic drought once established
Hardiness: Zones 2–9
Soil Preference: Prefers deep, moist, well-drained loam but adaptable to clay, alkaline soils, and compacted urban conditions
Sun Exposure: Full sun
Wildlife Value: Seeds eaten by birds and small mammals; provides habitat and nesting sites due to its broad branching architecture
Pests/Pathogens: Dutch elm disease (varies by cultivar; modern cultivars/hybrids show resistance), leaf miners, European elm scale, aphids
Planting Recommendations: Conditionally recommended for sites along the Front Range, due to susceptibility to Dutch elm disease select disease resistant varieties. Structural pruning is critical for many hybrid varieties to maintain a dominant leader.
Information Sources:
Front Range Tree Recommendation List
Michael Dirr, Manual of Woody Landscape Plants
Michael Kuhns, Trees of Utah and the Intermountain West
