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American mountain-ash identification: leaves, bark, fruit and twigs
American mountain-ash, Sorbus americana, is a native tree in Pennsylvania. How to recognize it by its leaves, bark, fruit and twigs, and how to tell it from look-alikes.
Alternate, compound leaves. Compound leaves 6 to 10 inches long with 11 to 17 narrow, toothed leaflets 2 to 2 1/2 inches long. Bark: Smooth grayish brown with many dots, later cracked and scaly. Checked Nov. 14, 2026.
How to identify American mountain-ash
| Leaf type | Alternate, compound leaves |
|---|---|
| Leaves | Compound leaves 6 to 10 inches long with 11 to 17 narrow, toothed leaflets 2 to 2 1/2 inches long. |
| Bark | Smooth grayish brown with many dots, later cracked and scaly. |
| Fruit | Clusters of small red berries 1/4 to 3/8 inch, ripe in fall and hanging on. |
| Twigs | Shiny gray to reddish brown twigs. |
| Size and shape | Small tree up to about 40 feet, usually smaller; flat clusters of white flowers in late spring to early summer. |
From the Virginia Tech Dendrology fact sheet, in our own words.
Is American mountain-ash native to Pennsylvania?
The Pennsylvania Natural Heritage Program (PNHP) lists American mountain-ash as native to Pennsylvania.
See all 140 trees, with a 4-question identifier, in our Pennsylvania tree identification guide.
Trees that look like American mountain-ash
| Tree | Its leaves |
|---|---|
| Showy mountain-ash Sorbus decora | Alternate, compound leaves. Compound leaves 5 to 10 inches long, usually with 15 toothed leaflets 1 1/2 to 2 1/2 inches long. |
| European mountain-ash Sorbus aucuparia | Alternate, compound leaves. Compound leaves 5 to 8 inches long with small leaflets 1 to 1 1/2 inches long, toothed only on their upper halves. |
| White ash Fraxinus americana | Opposite, compound leaves. Compound leaves 8 to 12 inches long with 7 leaflets that are toothed or smooth-edged and paler underneath. |
Compare the leaves first, then the bark, fruit and twigs on each tree’s page.
Questions
How do you identify American mountain-ash?
Look for alternate, compound leaves. Compound leaves 6 to 10 inches long with 11 to 17 narrow, toothed leaflets 2 to 2 1/2 inches long. Bark: Smooth grayish brown with many dots, later cracked and scaly.
Is American mountain-ash native to Pennsylvania?
The Pennsylvania Natural Heritage Program (PNHP) lists American mountain-ash as native to Pennsylvania.
How big does American mountain-ash get?
Small tree up to about 40 feet, usually smaller; flat clusters of white flowers in late spring to early summer.
How can you tell American mountain-ash in winter?
Check the twigs and bark. Twigs: Shiny gray to reddish brown twigs. Bark: Smooth grayish brown with many dots, later cracked and scaly.
What tree looks like American mountain-ash?
Showy mountain-ash, European mountain-ash, White ash. Compare the leaves first.
Sources: Virginia Tech Dendrology (Sorbus americana fact sheet); Pennsylvania Natural Heritage Program, PA Vascular Plant List (native or introduced status). Checked Nov. 14, 2026.
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