Juglans nigra - Black Walnut
The black walnut is one of America’s mighty arboreal giants. Standing at over 70’ feet tall this tree was coveted by pioneers and Native Americans alike. The tree is like its cousins the English and Persian walnut. Squirrels and humans are highly attracted to the nutritious nuts of the tree.
Scientific Name: Juglans nigra
Common Name: eastern black walnut, black walnut
Plant Family: Juglandaceae (walnut family)
Etymology: Juglans comes from the Latin name jovis meaning “of Jupiter” and glans meaning “an acorn.” Specific epithet means “black,” in reference to the dark bark and nut.
The black walnut was an important tree for early American settlers. It was and is still highly prized for its wood and its nut. The nut was eaten in different forms and capacities: being crushed up, added to soup, and just plain. Native Americans tribes like the Menominee, Chippewa and Cherokee used the nut to make brown and black dyes. Black walnut was used by the Appalachian, Cherokee, Comanche, Iroquois, and Rappahannock to treat athlete’s foot, hemorrhoids, and as an insecticide. The Iroquois made food and drinks out of it, crushing and boiling the fresh nuts to make a beverage. They would mix the crushed nuts in bread, sometimes adding fruit. The Iroquois also used the nut in soup, pudding, and for rituals involving the false face society. Medicinally, the Iroquois used it as a purgative, insect repellent, and dermatological aide. The Cherokee used the bark as a cathartic.
Native from Massachusetts through southern Ontario to South Dakota, south to Florida and Texas. In Missouri, black walnut typically occurs in rich woods, in valleys along streams, and in open upland woods throughout the USA.
How to Identify
The fruits are 4-6 cm in diameter and spherical shaped. They can be found in groups of 2-3 or solitary. The fruits have a thick, semi-fleshy, greenish yellow husk covered with short hairs. The nut is circular with rounded ridges. The bark of the black walnut can range from brown to dark grey. Yellowish-green flowers appear in late spring (May-June). The fall color of the tree is a very vibrant yellow, while the leaves typically are ovular and end in a point. The leaves run parallel up the branch.
The nutrients in the black walnut have been correlated with the prevention and/or attenuation of several types of diseases, including cancer, diabetes, and neurodegenerative conditions. Other nutrients that are also present in the black walnut include dietary fiber, folate, phytosterols, protein, melatonin, etc., which have been linked with multiple human health-promoting properties. The black walnut has been used successfully as an alley crop in the midwest.
The black walnut will kill some other plants, especially non-natives, planted near it due to the presence of the toxin juglone. The black walnut also gets very large so planting it in an appropriate place is crucial. It is hard to transplant due to its deep taproot. The black walnut also may not bear fruit until its 20th year.
- USDA Hardiness Zone: 4-9
- Native Range: Eastern and Midwestern United States
- Forest Garden Layer: canopy
- Permaculture functions: wood, edible fruit, shade, shelter for wildlife
- Soil moisture: moist
- Soil texture: Moist, rich soils. Sandy loam, medium loam, clay loam, acid-based.
- Height: 72 to 100 feet
- Spread: 60 to 75 feet
- Growth rate: 3’ to 4’ feet a year
- Sun: full sun
- Bloom: April, May
- Attracts: birds, butterflies
- Tolerates: weather hardy
- Drawbacks: slow growing, kills other plants around it, husks can be messy
- Câmara, Cristiane Rodrigues Silva, and Vicki Schlegel. “A Review on the Potential Human Health Benefits of the Black Walnut: A Comparison with the English Walnuts and Other Tree Nuts.” International Journal of Food Properties, vol. 19, no. 10, Oct. 2016, pp. 2175–2189. EBSCOhost, doi:10.1080/10942912.2015.1114951.
- Wolz, Kevin J., and Evan H. DeLucia. “Black Walnut Alley Cropping Is Economically Competitive with Row Crops in the Midwest USA.” Bulletin of the Ecological Society of America, vol. 100, no. 1, Jan. 2019, p. N.PAG. EBSCOhost, doi:10.1002/bes2.1500.