Rowan mountain ash (as known as European mountain ash or rowan) is a small to medium sized tree that produces bright orange/red berries. It can spread in forests and open areas and shade out other species.
The last tip of rowan mountain ash leaflet is generally even with the tips next to it as opposed to native mountain ash species where there is a projecting point at the end of the leaflets.
Rowan mountain ash buds have gray hairs and are not sticky.
Rowan mountain ash has clusters of white, 5-petaled flowers. Photo credit: Tom DeGomez, University of Arizona, Bugwood.org
Rowan mountain ash has clusters of bright red-orange berries.
Bark is smooth and gray.
Rowan mountain ash can grow along trails and in shaded areas.
Description
Appearance
Rowan mountain ash is a tree that commonly reaches about 40 feet tall but can grow taller. It produces clusters of small white flowers followed by clusters of orange/red berries.
Leaves and stem
Leaves attach to the stem one at a time in an alternating pattern on the stem. It has compound leaves that are composed of 9-15 leaflets per leaf. The leaflets are opposite one another with the exception of one leaflet at the tip of the leaf. Leaflets are 1 – 1.5 inches long and the leaf as whole can be up to 10 inches long. Leaflets have toothed edges. The last tip of a rowan mountain ash leaflet is generally even with the tips next to it as opposed to native mountain ash species where there is a projecting point at the end of the leaflets. Both the upper and lower sides of the leaflets have hairs. Rowan mountain ash buds have gray hairs and are not sticky. See the Minnesota Department of Agriculture mountain ash identification story map for detailed images.
Young trees have light gray, mostly smooth bark with visible lenticels (pores). The bark on older trees is dark gray and rougher and more fissured.
Flowers
It has clusters of small, white flowers. Individual flowers are less than half an inch wide and have five rounded petals. The green sepals (modified leaves) that cover the base of the flower have white hairs.
Seeds
Rowan mountain ash produces clusters of orange/red berry-like fruits. The berries are about 3/8 inch in diameter, and each contains one or two small brown seeds.
Roots
Roots can spread widely in a horizontal direction out from the trunk, but generally only penetrate about 3 feet deep into the ground.
Biology
Rowan mountain ash are small trees that can grow to 40-60 feet tall. Trees as young as 10 years old can start producing seeds. Birds and mammals can eat the fruit and spread the seeds to new areas.
Origin and spread
Rowan mountain ash is native to Europe and Asia. It has been planted in Minnesota as an ornamental tree. It has spread from planted areas into natural areas. It the United States its distribution is mainly in the northern states.
Refer to EDDMapS Distribution Maps for current distribution.
Don't be fooled by these look-alikes
American mountain ash, Sorbus americana (native) – The buds have few to no hairs and can be sticky while the buds on rowan mountain ash have many gray hairs and are not sticky. These buds are most visible in the winter, but can be seen throughout the year. In American mountain ash, the point at the tip of the leaflet projects out longer than its neighboring points, while last tip of rowan mountain ash leaflet is generally even with the points next to it. View the mountain ash comparison webpage (Minnesota Department of Agriculture) for details and photos of various differences.
Showy mountain ash, Sorbus decora (native) – The buds have few to no hairs and can by sticky while the buds on rowan mountain ash have many gray hairs and are not sticky. In showy mountain ash, the point at the tip of the leaflet projects out longer than its neighboring points, while last tip of rowan mountain ash leaflet is generally even with the points next to it. View the mountain ash comparison webpage (Minnesota Department of Agriculture) for details and photos of various differences.
Common elderberry, Sambucus canadensis (native) and red berried elder, Sambucus racemosa (native) – These species are shrubs that don’t reach more than 14 feet in height. Like rowan mountain ash they have compound leaves with leaflets, however they have opposite leaves (leaves attach to the stem in pairs with the two leaves opposite one another) while rowan mountain ash leaves have alternate leaves (leaves attach to the stem one at a time).
Black ash, Fraxinus nigra (native), green ash, Fraxinus pennsylvanica (native), and white ash, Fraxinus americana (native) – Although rowan mountain ash has the name “ash” in it, it is not an ash tree. Like rowan mountain ash they have compound leaves with leaflets, however ash trees have opposite leaves (leaves attach to the stem in pairs with the two leaves opposite one another) while rowan mountain ash leaves have alternate leaves (leaves attach to the stem one at a time). Ash trees do not produce berries while rowan mountain ash does.
American mountain ash and showy mountain ash have few to no hairs on their buds and the buds can be sticky. Rowan mountain ash has many gray hairs and is not sticky. Photo credit: Minnesota Department of Agriculture
American mountain ash and showy mountain ash have more pronounced tips at the end of their leaflets than rowan mountain ash. Photo credit: Minnesota Department of Agriculture
Common elderberry and red berried elder (pictured) have compound leaves that attach to the stem in pairs with the two leaves opposite one another. Photo credit: Robert Vidéki, Doronicum Kft., Bugwood.org
The native ash trees such as black ash (pictured) have compound leaves that attach to the stem in pairs with the two leaves opposite one another. Photo credit: Rob Routledge, Sault College, Bugwood.org
Regulatory classification
This species will become Minnesota Department of Agriculture Specially Regulated Plant in January 2026 beginning a three-year phase out period for commercial production. Then in January 2029 it will become a restricted Noxious Weed, meaning it would become illegal to import, sell, or transport.
Threat to Minnesota
Has been found to spread into natural areas and become a dominant plant in wooded areas and along trails. Can interfere with the regeneration of native forest species.
Can harbor a variety of pest species including fireblight, sun scald, crown gall, cankers, rusts, scab and stem borers.
What you should do
One way that invasive plant seeds and fragments can spread is in soil. Sometimes plants are planted purposefully. You can prevent the spread of invasive plants.
PlayCleanGo: Stop Invasive Species in Your Tracks
REMOVE plants, animals and mud from boots, gear, pets and vehicles.
CLEAN your gear before entering and leaving the recreation site.
STAY on designated roads and trails.
PLANT non-invasive species.
Native substitutes
American mountain ash (Sorbus americana)
Showy mountain ash (Sorbus decora)
Nannyberry (Viburnum lentago)
Kentucky coffee tree (Gymnocladus dioicus)
American mountain ash can reach 30 feet tall and is generally found in the northeastern part of Minnesota.
Showy mountain ash can reach 30 feet tall and needs well-drained soils.
Nannyberry is a shrub that can reach 20 feet tall and has white flowers and edible blue/black fruits.
Kentucky coffee tree can grow 50 – 100 feet tall and produces large seed pods.
Control methods
Mechanical control can be done by digging or pulling young plants by hand or with equipment.
Herbicide control can be done using systemic herbicides, which are taken up by plants and move within the plant, killing leaves, stems, and roots. Cut plants will resprout if the stump is not treated with herbicide after cutting. Immediately after cutting (within 2 hours), apply an herbicide containing triclopyr (Garlon 3A/Vastlan, Garlon 4, or other brush killers with triclopyr) or glyphosate to the cut stump to prevent re-sprouting. Always follow label instructions for herbicides. Herbicides can be applied to cut stumps with a paintbrush, wick applicator such as a dauber or "buckthorn blaster," or a low volume sprayer. In cases where more than a few plants are treated, add an indicator dye (available where pesticides are sold), such as Mark-It Blue, to the herbicide to mark which cut stumps you have sprayed.
For basal stem treatment, a method that applies chemical through the bark, low volume spray applications can be made with Garlon 4, Pathfinder II and similar oil-based products. This application method uses triclopyr ester mixed with an oil diluent (i.e. Bark Oil Blue, kerosene) applied directly to the bark of Amur cork tree from the root collar up about 12-18 inches. An ultra-low volume spray wand should be used to minimize herbicide use and reduce the potential for non-target injury.
Reporting
Report new occurrences by submitting a report through EDDMapS, emailing Report A Pest, calling Report A Pest (1-888-545-6684), or contacting your local county agricultural inspector.
Resources
Identifying mountain ash species in Minnesota (Minnesota Department of Agriculture)
Rowan (European) mountain ash identification (North Carolina State University)
Managing woody species (University of Minnesota)