common hackberry (Celtis occidentalis)
First place champion common hackberry in Denver.
Species info:
Leaves: Alternate, simple, ovate to oblong-ovate, about 4" long and 2" wide. Leaf margins are serrated; tip is acuminate. Upper surface is rough to the touch; underside paler and often bears small nipple-like galls.
Leaflets: None (simple leaf).
Leaf Surface: Sandpapery and rough on the upper surface; lighter and slightly pubescent or smooth beneath; galls commonly present.
Bark: Gray and smooth when young; develops distinctive corky-warty ridges and bumps with age—one of the tree’s most recognizable identification features.
Flowers: Small, greenish, and inconspicuous; appear in spring.
Fruit: A small, round drupe approximately ¼ inch in diameter; ripens to dark purple-brown in September–October; edible to wildlife.
Botanical: Celtis occidentalis
Family: Ulmaceae
Mature Height: 40–60 feet (up to 70 feet in optimal sites)
Canopy Spread: 30–50 feet; vase-shaped and arching at maturity
Foliage Type: Deciduous
Tree Shape: Broadly oval to vase-shaped crown; irregular and scattered branching in youth
Growth Rate: Medium to fast; can reach 30 feet in the first 20 years
Flower: Inconspicuous
Fruit: Minimal
Fall Color: Yellow to yellow-green; not considered ornamental
Water Use: Low to moderate; drought tolerant once established
Hardiness: Zones 2–9
Soil Preference: Adaptable to most soils including clay, loam, alkaline, and compacted soils; tolerates drought and urban conditions
Sun Exposure: Full sun; tolerates light shade
Wildlife Value: Fruits (drupes) are relished by birds and small mammals; provides nesting habitat and cover
Pests/Pathogens: Hackberry nipple-gall psyllid (causes round galls on leaf undersides) and witches’ broom (associated with eriophyid mites and fungal pathogens), which are mainly aesthetic concerns and rarely threaten tree health. Squirrels commonly gnaw on bark, which can girdle branches and/or trunks.
Planting Recommendations: Recommended for most areas as it is well adapted throughout the plains and foothills (especially at elevations between 4,000–7,200 feet). Structural pruning when young is important for maintaining a strong dominant leader.
Information Sources:
Front Range Tree Recommendation List
Michael Dirr, Manual of Woody Landscape Plants (University of Georgia, 1990)
Michael Kuhns, Trees of Utah and the Intermountain West (Utah State University Press, 1998)
