Virtual Nature Trail
      
Black Walnut  (Juglans nigra)Black Walnut Tree

The black walnut tree is one of the scarcest and most commercially valuable trees in the eastern hardwood forest. The black walnut has compound leaves that are longer and more pointed that those of the white ash. The leaves also contain a larger number of leaflets (between 9 and 21) than the ash. The black walnut produces an edible nut that is encased in a thick green or brown husk. There are probably some of the nuts in their husks on the ground around the walnut tree. You have to be careful handling these nuts, though, because of the black dye that is found in the husks. Many animals eat these walnuts including squirrels, turkeys, raccoons and bears.

Black walnut trees often affect the kinds and densities of plants that grow around them. The walnut leaflets are rich in chemicals called "polyphenols" that are an excellent defense against insects. These polyphenols, though, accumulate in the soils around the walnut trees (the walnut roots also secrete these polyphenols) and act as a controlling, ecological force within the soil ecosystem. Careful examination of the ground vegetation around the black walnut tree will reveal an vegetative ecosystem that is different from those found even under the adjacent hardwood trees.



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