Black Walnut

Juglans nigra L.

     

   

All photographs are copyrighted and are the property of E. Brunner.

Family:  Juglandaceae

Native or Introduced to Illinois: native 

Natural Habit in Illinois:  bottomland and floodplain woods

Leaf:  The tree has large, pinnately compound leaves, 12 to 24 inches long with 15 to 23 leaflets. The leaf stems are covered with fine hairs, but are smoother than butternut. The leaflets are 2-1/2 to 3 inches long, yellowish green in color, tapering at the end and toothed along the margin.

Flower: Male flowers are single-stemmed catkins, 2 1/2 to 5 1/2 inches long. Female flowers on short spikes near twig end, yellow-green in color. Present April to June.

Fruit:  The fruit is a large, rounded, brownish black nut with a hard, thick, finely ridged shell enclosing a rich, oily kernel. The kernel is edible and highly nutritious. The nut is enclosed in a solid, non-splitting husk, and is borne on the tree singly or in pairs.

Twig:  The twigs are brownish, stout, blunt and with prominent leaf scars. The pith is cream colored and chambered, dividing into thin plates or segments.

Bark: The thick bark is dark brown in color and divided by deep fissures into rounded ridges. It has a chocolate brown under-color when broken from the tree.

Size/Form/Shape: A medium-sized tree that develops a straight, clear bole with a narrow crown under competition. Twigs and branches quite stout.

Other:  This is a valuable timber tree. The wood is heavy, hard, strong, close-grained, and very durable in contact with the soil.  The nut kernel is edible and is used in a variety of products such as ice cream and candy.  The nut hulls were once used as a dye.  The roots release a toxic material that can kill other plants growing above them.  The tree is of high value for songbirds, woodpeckers, game mammals.

Ethnobotanic:  The bark of black walnut was used by many native groups, including the Cherokee, in tea as a laxative and chewed for toothaches.  The Cherokee also ate the fruit of the black walnut.  The Chippewa and the Cherokee used the bark to make brown and black dyes.  The Comanche created a paste from the leaves and husk of the fruit for treatment of ringworm.  Black walnut was also used by the Appalachian, Cherokee, Comanche, Iroquois, and Rappahannock to treat athlete’s foot, hemorrhoids, and as an insecticide.  

County Distribution Map for Illinois:  

Sources for the Sullivan Middle School Tree Identification Guide were obtained though the use of the following sites:

• Illinois Plant Information Network (ILPIN) @ http://www.fs.fed.us/ne/delaware/ilpin/ilpin.html#Background
• List of Woody Plants Native or Naturalized in Illinois @ http://www.inhs.uiuc.edu/~kenr/woody.html
• Tree Species @ http://ostermiller.org/tree/species.html
• Index to Eastern/Central Trees @ http://www.arborday.org/trees/ECtreelist.html
• ISU Forestry Extension Identification of Common Trees of Iowa @ http://www.extension.iastate.edu/Pages/tree/
• Key to Leaves of Virginia Trees @ http://www.fw.vt.edu/dendro/forsite/key/intro.htm
• List of Native Trees for Use Along Roadsides in Illinois @ http://www.inhs.uiuc.edu/~kenr/treetable.html
• The PLANTS Database @ http://plants.usda.gov/

The information below is from the National Arbor Day Foundation.  This information can be viewed in the original (source) form by visiting The National Arbor Day Foundation at http://www.arborday.org.

GROWING REQUIREMENTS/RATE
Sun Exposure: Full sun all day in the north. Average fruit tree needs a minimum of 6-8 hours of sunlight daily. All need water and are not drought resistant.
Soil Type: deep, rich, moist, well-drained
Growth Rate: Medium

Hardiness Zones: 4 - 9
The Black Walnut can be expected to grow in the temperature extremes of the zones shown in color in this arborday.org hardiness zone map.