Black Walnut

Juglans nigra L.

Black walnut, Juglans nigra, may also be known as eastern black walnut or American walnut. The tree once grew abundantly in the eastern bottomland forests, where the soil was deep and rich. Trees 150 feet tall with 50-foot clear stems and 6-foot diameters were not uncommon. Black walnut was the number one prized fine hardwood in America at a time before the use of veneers. Early colonists exported the wood to England from Virginia as early as 1610. Solid walnut wood was used in every sort of homemade furniture imaginable, during the Colonial and Federal periods, but rarely was the fine grain appreciated. Most pieces were covered with a coat of paint. The rage for walnut as a fine furniture wood occurred in a period from 1830-1860, during the popularity of the Empire, Victorian, and Revival styles. Unfortunately by this time, black walnut wood was already becoming scarce.

During pioneer times in the Midwest states, black walnut was still very abundant, although the extremely large trees were already gone. The tree was often cut for rudimentary things as split rail fences. Millions of railroad ties were made from walnut, since it resisted rot when in contact with the soil.

The latest heyday of black walnut occurred in the 1970s when walnut was king and prices went through the ceiling. Since then, because of economic factors, export tariffs, and preferences for lighter woods, walnut temporarily took a back seat to black cherry, red and white oak, pecan, and even sugar maple. Black walnut is now making a comeback and is competing with black cherry and white oak as one of the fine North American hardwoods.

Black walnut never faltered in its use as gunstock material. It is unsurpassed, since no other wood has less jar or recoil, it doesnt warp, shrink or splinter, and it is light in proportion to its strength. The smooth, satiny surface makes it easy to handle. The U.S. Government used black walnut gunstocks for generations and it is still the favored wood for shotguns and rifles used by hunters and sportsmen.

Black walnut trees of 150 feet in height still can be found, but are very rare. Natural, forest-grown trees are best for lumber and veneer since the competition from other trees tend to make them grow straight and columnar. Trees grow faster when open-grown in fields. Here, they have broad, rounded crowns, with many branches, usually lower to the ground.

The bark is black, thick and deeply furrowed. When scraped with a knife, it reveals a chocolate-covered sub-surface. The twigs are stout, greenish or orange-brown in color, and may be hairy or smooth. The pith (inner portion of the twig) is dark brown in color and is partitioned (chambered) when sliced with a knife. The only other tree in the Midwest that exhibits this characteristic is the butternut, Juglans cinerea. The leaf scars of black walnut are alternate and shield shaped, with 3 bundle traces. This is the point of attachment of the leaf with the twig. The buds are fairly rounded at the tip, pale brown or gray in color, softly hairy, and up to 1/ 2inch long.

The leaves are alternate (occurring at different points along the twig), and pinnately compound. A compound leaf consists of many leaflets, which make up a single leaf versus a simple leaf, which has but one part. A leaf can be determined from a leaflet by locating a lateral bud at its base on the twig. An example of a simple leaf is a sugar maple leaf. A black walnut leaf may be made up of 15-23 leaflets. Each leaflet may be 3 inches long and 1- inches wide. Therefore, the entire leaf may be 1 foot long or longer. The leaflets are broadly lance-shaped and pointed at the tip. They are rounded and asymmetrical at the base. If you fold a leaf (any species) in half, and both halves match perfectly, the leaf is considered to be symmetrical. If it does not match together, it is considered to be asymmetrical. The leaflets are toothed on the edges and are yellow-green on the upper surface and paler and hairy on the lower surface. When crushed, the leaves have a distinct "walnut" smell.

The flowers are borne separately, but on the same tree. They appear as yellow-green catkins (think of birch trees), and appear when the leaves are partly grown. The staminate (males), are most abundant and are thicker when compared to the pistillates (females), which are fewer in number and smaller. The flowers have no petals.

The fruits (walnuts) occur singly or in groups of 2 or 3. They are spherical in shape and 2 inches or larger in diameter. The outer husk is yellow-green, but quickly darken and turn black when they fall to the ground. The inner nut has a very hard shell, is dark brown in color, deeply ridged and has a sweet tasting edible nut. Remember to wear rubber gloves when picking walnuts because the nuts will stain your hands and it is difficult to remove.

The black walnut nut industry is also very profitable. The rich tasting black walnut extract flavoring is made from these nuts, as well as black walnut ice cream. The shells are used in the abrasives industry. Walnut trees grown for the nut industry are usually open-grown trees with large crowns to produce a high volume of fruit versus a narrower crown in a natural stand, producing straighter trees with fewer limbs.

The natural range of black walnut is western Massachusetts and Connecticut, south to the North Carolina coast, southwest through Georgia and westward through the Gulf states to eastern Texas, north through Oklahoma to southern Nebraska, and eastward through the southern regions of the northern Lake states. It is scattered in New York and can be found in extreme southern Canada.

Black walnut grows in association with a variety of hardwood tree species. These include most species of the eastern oaks, the ashes, yellow poplar, beech, sugar and silver maple, basswood, river birch, most hickory species, hackberry and sugarberry, black cherry, cottonwood, the elms, black gum, sweet gum (not related), and to a lesser extent, many smaller trees and shrubs.

A closely related tree, the butternut, or white walnut, Juglans cinerea, is becoming very rare because of a fungal disease called "butternut canker". This can be compared to the devastating "chestnut blight" on the American chestnut tree. Young butternut trees are difficult to distinguish from young walnut trees. Bark characteristics and fruit cannot be used. As a rule of thumb, the terminal bud of a butternut is more elongated rather than rounded and the terminal leaflet is present on butternut, while it is either absent, dwarfed, or occurs as 2 small leaflets in black walnut. A mature butternut has distinct elongated light gray plates on the bark. The fruit is also spherical in shape, while black walnut is rounded.

Black walnut leaves, fruits and twigs contain a chemical called "Juglone" which is alleopathic. It is a growth inhibitor to some species of plants such as tomatoes or apple trees. Therefore, never plant a walnut tree near these species you wish to grow. This is natures way of eliminating competition so that the walnut tree is able to take up all available nutrients. Unfortunately, other plants are alleopathic to walnut trees. These are fescue grass and goldenrod. These species should be eliminated by herbicide if you are growing walnut trees.