American Mountain Ash

The American mountain ash (Sorbus americana), also known as mountain ash or roundwood, is a deciduous small to medium size tree, attaining a height of 30 feet (maximum 71 feet), and a trunk diameter of more than 1 foot. It does not grow rapidly and is considered a short-lived species.

The leaves are alternate, pinnately compound, 6 to 10 inches long with lance-shaped leaflets that are 2 to 3 inches long; fine and sharp toothed margins, dark yellow-green on top and paler beneath.

light gray-brown American mountain ash bark
American Mountain Ash Bark, Photo by Keith Kanoti, Maine Forest Service, Bugwood.org

The fruits are pomes (berry-like), 1/4 inch in diameter, in large clusters, and an orange-red color when mature.

Hardiness: Zones 3 through 9

Growth Rate: Moderate to Fast

Mature Shape: Slightly pyramidal, upright with a rounded crown

Height: 50 to 80 feet

Width: 50 to 70 feet

Site Requirements: Native to Iowa, ash trees grow best in full sun and moist, well-drained soils. Ash trees are tolerant of a wide range of soil conditions.

Flowering Dates: May - July

Seed Dispersal Dates: August - March

Seed Bearing Age: 15 Years

Seed Bearing Frequency: Yearly

Seed Stratification: Seeds need cold stratification for 2 months at 34°F to 40°F

The twigs are thick, smooth, and gray to red color. The bark is light gray-brown, smooth on younger trunks, and rougher on older ones.

Considered a beautiful ornamental tree with no commercial value, it is commonly found in disturbed forest edges, cold swamp and bog margins, and rocky outcrops. Distinctly a northern species, it ranges from Newfoundland to Manitoba south to the northern portions of the United States and along the Appalachian Mountains to North Carolina.

American ash leaves
American Mountain Ash Leaves - Photo by Keith Kanoti, Maine Forest Service, Bugwood.org

Diseases that Can Affect American Mountain Ash

Insects that Can Affect American Mountain Ash

 

Red, berry-like American ash fruit
American Mountain Ash Fruit, Photo by Keith Kanoti, Maine Forest Service, Bugwood.org