single leaf ash (Fraxinus anomala)

First place champion Scotch pine in Fort Collins at City Park.

Species info:

Leaves: Mostly simple (unlike most ashes); bright green, smooth, glossy, and slightly toothed along the margins

Leaflets: Occasionally a few compound leaves, but typically single leaves per node

Leaf Surface: Smooth and shiny green; turns brilliant yellow in fall

Bark: Dark brown to gray; slightly furrowed with age

Flowers: Inconspicuous; tree is dioecious (separate male and female trees)

Fruit: Winged samaras up to ¾ inch long; hang in clusters; mature mid-summer and may persist through winter

Botanical: Fraxinus anomala

Family: Oleaceae

Mature Height: Typically 10–20 feet (can vary depending on site moisture)

Canopy Spread: 10–15 feet; rounded when young, becoming upright and elliptical at maturity

Foliage Type: Deciduous

Tree Shape: Irregular, rounded to upright-elliptical; often multi-stemmed

Flowers: Inconspicuous; appear in spring before or with leaves

Fruit: None

Fall Color: Brilliant yellow; highly ornamental

Water Use: Low; tolerant of drought, heat, and high pH soils

Hardiness: Zones 5–7

Soil Preference: Adapted to dry, rocky, or well-drained soils; thrives in canyon bottoms or runoff areas where moisture accumulates

Wildlife Value: Seeds provide food for birds and small mammals; canopy offers limited cover

Pests/Pathogens: No major pest issues observed in native habitat; however, all ash species are susceptible to Emerald Ash Borer (EAB) in infested regions

Notable Traits: Native to western Colorado and southern Utah; highly tolerant of arid conditions and alkaline soils;

Planting recommendation: Ash trees are no longer recommended for planting in Colorado due to the presence of Emerald Ash Borer (EAB); refer to the Front Range Tree Recommendation List for alternatives

Information Sources:

• Trees of Utah and the Intermountain West, Utah State University Press, 1998.

• Michael Kuhns. Fire Effects Information System. USDA Forest Service.