The Black Walnut is a very large tree, not to be used in the small residential landscape situation. Native to North America, mostly along the rivers from Ontario in the north to Georgia and Florida in the south and as far west as central Texas. Reaching heights of 50-75 feet in height and often equal in width when grown in most situations, however the species may even reach in the 100 foot range.Hardy in zones 4-9. The leaves of the Black Walnut are pinnately compound, and rather large. (12-24″ long) You will find anywhere from 15-23 leaflets arranged alternately. The ovate oblong leaflets are 2-5″ long and 3/4-2″ wide and dark green in color. When the leaves are crushed the emit a fragrant scent. Dark brown to grey deeply furrowed bark forms a rough diamond pattern along this tree’s massive stem. The fruit of this impressive specimen is a rather large nut 1.5-2″ in diameter with light green surface. Great flavor.
As this tree matures there is difficulty in successful transplantation as it forms quit an extensive tap root. Care should be given as to the site location of this tree due to its large overall height and spread. Black walnut will compete for root space with other plants as well as affect others with an organic compound it forms called Juglone. Juglone is found in the leaves, bark and roots and is toxic or growth stunting to many types of plants often creating a difficult landscaping situation. Juglone has been used for a coloring agent in foods as well as cosmetics.
Black Walnut is highly prized for its dark-colored true heartwood. It is heavy and strong, yet easily split and worked. Walnut wood has historically been used for gun stocks, furniture, flooring, coffins, and a variety of other woodworking products. It is so valuable that so-called “Walnut Rustlers” have been known to harvest it illegally by posing as forestry officials, cutting trees during the night, and even using helicopters to take them away quickly; such over harvesting has greatly reduced its numbers and range since colonial times.
This stately tree deserves a place in large landscapes, such as parks, estates and campuses.
Black Walnut (Juglans nigra) – Bark
Black Walnut (Juglans nigra) – Leaves, Nut