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Black Walnut Tree

Juglans nigra

Height: Usually about 75 feet, but it reaches 100 feet or more in mature forests  

Evergreen/Deciduous: Deciduous  

Lifespan: 100 to 200 years

Fall Foliage: Yellow, but no where near the vibrance of some true hickories  

Range: The bulk of the eastern United States, north to New York, west to the Great Plains; absent from much of the coastal plain   

Typical Habitat: Sunny areas with plenty of soil moisture   

black walnut tree leaves

The Black Walnut: A Combative Pioneer   

While it grows slowly once mature and turns into a very stately tree, the black walnut grows quite quickly when young. This is a capability that most pioneers possess, but the black walnut uses another trick to help stake its claim in new areas: It engages in chemical warfare.

Known as an allelopathic species, black walnut trees release compounds into the soil that prevent many other species from surviving. This way, the young trees don’t have to compete with other trees for nutrients and water in the soil.

Black Walnut Identification: Tips & Tricks

The black walnut is generally pretty easy to identify. First, simply look for the tree’s large nuts, which are often present in large numbers and visually apparent. If no nuts are apparent, turn your attention to the tree’s compound leaves.

Black walnut leaves are about 12 to 24 inches long and adorned with 15 to 23 toothed leaflets. The terminal leaflet (the one at the end of the leaf) may be present, but it is most commonly absent. This gives the leaves a relatively distinct look and makes it easier to distinguish them from the leaves of pecan trees (Carya illinoisnensis).  

The Black Walnut: Additional Information

Going nuts for more information about this tree?

(I’m really, really sorry about that.)

Allow me to make amends with some top-notch sources for black walnut tree info:

  • U.S. Forest Service: A comprehensive guide to the species that covers everything from growth habits to ecology to fire susceptibility.
  • Missouri Botanical Garden: Provides an overview of the black walnut, including basic info as well as several high-quality photographs.
  • Florida IFAS Extension: A broad overview of the species, including horticultural information.    

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