Black walnut

Juglans nigra
Family: Juglandaceae

Natural Historyblack walnut
Leaves and fruit of black walnut
Photo credit: Larry Korhnak, University of Florida

The black walnut has long been recognized as one of the most valuable North American trees.  Unfortunately, ruthless cutting has caused its almost complete extinction in certain areas, making it one of the scarcest and most coveted native hardwoods.  American colonists used the wood for fence rails and fuel.  The master craftsmen of Queen Anne discovered the wood's excellent potential in cabinetry during Colonial times.  During the civil war, the wood was used in the manufacture of gunstocks. Later in the First and Second World Wars, it was used for both gunstocks and airplane propellers. Today, about 65% of the annual wild harvest comes from Missouri.

Habitat & Range

The black walnut grows on deep, moist, fertile soils of bottomlands and gentle slopes, where it occurs as an occasional tree in association with other hardwoods.  It is found from Massachusetts through southern Ontario, to central Nebraska; south to Texas, Georgia, and northern Florida. It is a shade intolerant species.

Wildlife Use

The nut of the black walnut serves as an important food source for squirrels as well as other wildlife species.

Human Use

Today black walnut is the most popular wood used for fabricating solid and veneer furniture. Black walnut nuts are shelled commercially in the United States, the nutmeat providing a distinctive, natural flavor for use in several foods such as ice cream, bakery goods and confections. The nut has a high nutritional value and is therefore used in other foods such as salads, fish, pork, chicken, vegetables and pasta dishes.


 

Identifying Characteristics

Size/Form: Black walnut is a medium-sized tree, growing 70 to 130 feet in height and 2 to 4 feet in diameter. In dense stands, it commonly produces a long, clear bole that supports a small, narrow, open crown. Grown in the open, it develops a short trunk and a massive, spreading crown. The root system of this tree is deep and widespread.
Leaves: The leaves are pinnately compound, alternate, and deciduous. They generally have 15 to 23 leaflets on a central stalk 47 inches long. Leaflets are oval and tapered, growing 3 to 4 inches in length and 1 inch wide with acute apices. Leaflet bases are usually rounded. The middle leaflets are larger than those at either end of the leaf, with the terminal leaflet either small or missing. The top of the leaflet is smooth and yellowish-green while the underside has hairs. The leaflet margins are finely serrate. The rachis is hairy.
Twigs: The twigs are stout, brown to orange-brown. The pith is yellowish-gray and chambered.
Bark: Light brown and scaly when young. As the tree matures the color becomes a dark gray-brown to almost black with rounded intersecting ridges and deep furrows. The inside of the ridges is chocolate brown.
Flowers: Black walnut is a monoecious species. The male flower is a single-stemmed catkin, 2 to 5 inches long. The yellow-green female flower exists on short spikes near the twig end and blooms in late spring.
Fruit: A round, globular nut, up to 2 inches in diameter that is enclosed in a thick, succulent, yellowish-green husk. They are found in clusters of one to three. The seed is oily, sweet, and edible.
Similar Trees on the Florida 4-H Forest Ecology Contest List:
The fruit of black walnut is distinctive, but you can't rely on always having it available. Several other plants on our list also have alternate, pinnately-compound leaves.

 

Images

Click on any thumbnail to see a photo. Use left and right arrows to navigate. Use "esc" to exit the lightbox.

 

Learn More