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Eastern Black Walnut (Juglans nigra)

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Summary

A widespread and common tree native to eastern North America, valued for its nuts as well as its wood.

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Native

This tentative map is based on the FHWA's ERA. This data lacks information on Canada, but also overestimates native ranges, especially around the edges, as this post explains. We have not yet reviewed or fixed this map.

USDA Plants Profile for Juglans nigra

Illinois Wildflowers Page for Juglans nigra

Fire Effects Information System (FEIS) Article for Juglans nigra

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Habitat

Prefers full sun, moist conditions, and fertile soil. Found on a range of sites but most common and vigorous on deep, well-drained soils rich in nutrients, especially limestone soils. Growth is slowed on waterlogged soil or dry sites. Prefers similar soils to those ideal for Western agriculture.

Most common in bottomlands and floodplains. An early successional species, intolerant of shade and often not persisting long in forests in the absence of disturbance.

Well-adapted to fire, both in terms of fire-resistance and ability to rapidly colonized burned sites.

Life Cycle

Nuts germinate after a period of cold dormancy, usually after being buried by a squirrel. Some nuts do not germinate in the first year.

Seedlings quickly establish a deep taproot with numerous branching lateral roots. The first few leaves have fewer leaflets than normal, but quickly the new shoot has leaves more typical of this species. Seedlings are shade-intolerant and require high light conditions to survive, although there is enough energy stored in the nut for them to sometimes push up through competing vegetation to reach light.

Relative to other trees, leafs out relatively late in spring. Begins dropping leaves early, often starting mid-summer. Drought, insects, or disease causes trees to drop more leaves earlier, often with little to no long-term detriment to the tree.

Growth is rapid, and trees begin producing nuts around 8 years of age. Seed production is irregular, with large crops produced on average every 2 out of 5 years. Seed production peaks around 30 years and continues to about 130 years. Seeds mature in fall. Seeds are heavy and primarily dispersed by squirrels.

Younger trees are more likely to be top-killed by fire, but more likely to resprout vigorously from the root crown. Trees older than about 30 years are usually more resistant to fire, but less likely to resprout if top-killed. Resprouting is often vigorous on younger trees following cutting, making these plants somewhat hard to remove when growing unwanted in a garden setting.

Uses

Eastern black walnut is a highly desired wood for woodworking, due to its ease of working and rich, dark color, and good strength and physical properties. It is used in furniture, cabinetry, paneling, and various small objects. This species rapid growth and wide distribution makes it one of the more sustainable wood sources, although its populations have still be harmed by overharvesting due to the wood's desirability. More on Black walnut in the wood database.

The nuts of black walnut are edible, although they are more difficult to crack and slightly more bitter relative to English walnuts. Because of its strong flavor, it is often used as an ice cream flavor, where the sweetness of the ice cream balances the nut's bitterness.

Historically, black walnut has also been used as a dye plant, producing a dark brown color. It is sometimes still used as such by those interested in plant-based dyes or historically-accurate dying.

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