Spotting a walnut tree in the wild or your yard? These tips will help you confidently identify walnut trees—especially the American black walnut and common English walnut—using leaves, bark, nuts, and winter features.
1. Look at the Leaves
Walnut trees have large, pinnately compound leaves arranged alternately. Each leaf typically has 11–23 toothed leaflets, each 3–6 inches long, with no terminal leaflet on mature branches. Leaf margins are fine-toothed all around. Crushing a leaflet releases a mild citrusy, spicy aroma, unique to walnut trees.
2. Examine the Bark and Twigs (All Year Round)
Even in winter or when leafless, identification is possible:
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Mature walnut bark is thick, deeply ridged, and forms a diamond-shaped pattern in gray to almost black tones.
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Twigs are stout and rigid, with short, fuzzy terminal buds capped by gray down.
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If you take a twig and split it lengthwise, you’ll find chambered pith—a telltale sign.
3. Find the Nuts on the Ground
Walnut fruits are round, hard-shelled nuts enclosed in green husks—often messy after squirrels eat them. Common English walnuts are slightly elongated, while black walnuts are fully spherical. Clusters of fallen husks or nuts beneath a tree help confirm identification during autumn and winter.
4. Note Growth Habit & Tree Appearance
Walnut trees can grow between 30 and 130 feet tall, often with a straight trunk and open, rounded crown. Branches tend to extend horizontally off the trunk. They thrive in full sun, often along rivers, roadsides, and open woodlands. Gardens around walnut trees may show stunted plants due to juglone—a chemical they release.
5. Differentiate from Look-Alikes
Walnut trees are sometimes confused with Tree of Heaven (Ailanthus). Here’s how to tell them apart:
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Walnut leaflets are finely serrated and lack a terminal leaflet; Tree of Heaven leaflets are smooth with little “thumbs” and often include a terminal leaflet.
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Walnut bark is rough, furrowed, and dark; Tree of Heaven bark is smoother.
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Walnut nuts are large and round; Tree of Heaven spreads seed pods that are small and papery.
Conclusion
Identifying walnut trees is easier than you think—just combine observations of compound toothed leaves, aromatic foliage, deeply ridged bark, chambered twigs, and round nuts.
