Black Walnut Tree

Walnut has been a favored hardwood for many hundreds of years. Some of its uses include fine furniture, barns, floors, fences, and since it shrinks and swells less than any other wood, it is extremely popular with cabinet makers and gunsmiths.

The stain that results when the nutshells are opened, is so permanent that pioneers used it to dye cloth. Some of the harvested logs are made into veneer, then glued onto cheaper woods to make walnut furniture and paneling.

Relatives of Black Walnut

Close botanical cousins of the black walnut are the butternut, the hickory and the pecan tree. English walnut and Persian walnut (Carpathian walnut) are often grafted onto black walnut root stock. There is a chambered pith within the branch, that looks like a honeycomb. Only butternuts share this distinction with the black walnut. Leaves and the nuts themselves are easily recognizable, as is the smell, lack of leaf covering on buds, and sometimes large leaf scars on twigs. Squirrels seem to think the tennis-ball sized fruit should be a winter staple and can be seen running across the telephone wires with these heavy green husks in their mouths. You might encounter them left on your doorstep, buried in planters and window boxes, and under the tires of your car in the driveway.

Walnut grows best in the deep well-drained soils of the northern Missouri, but it is found over the eastern United States as far west as Nebraska, Kansas and Texas. Growing chiefly along bottomlands, in coves and on lower slopes, it prefers a deep, rich, moist but well-drained soil.

The Walnut Fruit

The black walnut fruit is a nutritious, oily nut kernel, inside a thick ridged shell, enclosed in a solid husk. Walnuts are an excellent source of Omega-3 fatty acids, proteins, and other nutrients, and are used in cooking and baking, as well as for their oil.

Toxic to Some Other Plants

The roots of the black walnut produce a substance known as juglone. Some plants grown within the root zone of the black walnut may be injured or killed within a few months. As the tree grows and its root zone expands, so does the “killing zone”. The affected plants include:

• Tomato
• Potato
• Blackberry
• Blueberry
• Azalea
• Mountain laurel
• Rhododendron
• Red pine
• Apple

Not all plants are sensitive to juglone. Many trees, vines, shrubs, groundcovers, annuals and perennials will grow in close proximity to a walnut tree. Since English or Persian walnut trees are sometimes grafted onto black walnut root stock, you should inquire of your nurseryman whether it will be safe to plant in the vicinity of the tree you purchase. If the tree is already a part of your landscape, you will need to choose carefully before planting shrubs and other plants which might be susceptible to juglone.

Sources:

Ostermiller.org

Ohio State University’s Ohioline