English
Polski
Deutsch
Українська
Black Walnut - Juglans nigra
Common Names: Black Walnut, Walnut, American Walnut, Eastern Black Walnut, Juglans nigra, Carya, Nogal Americano, Nogal Negro, Nux Persica, Nux Regia, Schwarze Walnuss, Noix de Perse, Noyer d’Amérique, Black walnut green, Walnoot, Noir
Latin Name: Juglans nigra
Origin: Asia, Europe, South America, North America
Short Introduction
The yield of Black Walnut nuts can vary significantly from year to year. Nut production may begin as early as the fourth year, but substantial yields are typically achieved after about 20 years, and trees can live up to 130 years. Germination of nuts in warm conditions can take several months, with the best results when the nuts are layered to reduce humidity. Seedlings begin to grow from April to May, and can grow about 1 meter annually, with growth rates increasing each year. Black Walnut is notably more frost-hardy than other walnut species, though it thrives best in warmer locations with rich soil and plenty of water at lower elevations. It will also grow in drier soils, though at a much slower rate. An important note is that Black Walnut is considered an allelopathic plant, releasing chemical compounds from its roots and other tissues to inhibit or limit the growth of surrounding plants, thereby gaining a competitive advantage. This trait is often considered undesirable in parks and gardens. Most commercial Black Walnut hulls are grown and harvested in the United States, with roughly 65% of the total yield produced by an American agricultural company based in Stockton, Missouri.
Detailed Description
A majestic tree with a rich tradition of therapeutic uses among Native Americans.
Botanical Information
Black Walnut (Juglans nigra) is a large, upright, deciduous tree reaching impressive dimensions—growing up to 20–40 meters tall and 15–25 meters wide. Its bark is deeply furrowed, dark gray, and forms distinctive diamond-shaped patterns. The leaves are compound, pinnate, and alternately arranged, measuring 30–60 cm in length and consisting of 15–23 pointed leaflets (each 7–10 cm long and about 3 cm wide) with finely serrated edges. The tree is monoecious, with male flowers as brown catkins and female flowers clustered in groups of 2 to 5 at the ends of branches. The fruits are spherical, very hard, 4–6 cm in diameter, green-brown, aromatic (with a pungent or spicy scent), and contain edible kernels that ripen from October to November.
Origin and Distribution
Black Walnut is native to the eastern part of North America, commonly found along rivers and valley bottoms from southern Ontario west to southeastern South Dakota and south to Georgia, northern Florida, and southwest into Texas. Human activity and agricultural interest spread the tree into Europe, Central Asia, and China during the 17th century. Initially planted as an ornamental tree in estate gardens, it is now a common feature in public parks. The first Black Walnut in the Czech Republic was recorded in 1835; the largest specimen in the country grows in the park at Kvasice Castle (Kroměříž District).
Usage / Dosage
Black Walnut is a valuable commercial hardwood, prized for both its nuts and its dark, easily workable timber. Trees can be cultivated for one purpose or both. In the culinary world, Black Walnut is popular for ice cream, baked goods, confectionery, and especially for autumn cakes, pies, cookies, and sweets. The hulls can be soaked in syrup or alcohol-based infusions to flavor beverages.
The pigments juglone, plumbagin, and tannin are natural dyes with a historic role in coloring hair, handmade products, floors, furniture, and public property. Even today, the hull is used as an abrasive polish, as a filter for tar purification, and as an ingredient in cosmetics. Fresh hull extract appears yellowish-brown and darkens over time.
Indigenous healers and shamans used Black Walnut hull extracts in cleansing rituals against parasitic infections, believed to detoxify the intestinal tract and support immune health. Before the advent of vitamins and minerals, Black Walnut was commonly used to treat ulcers, wounds, scurvy, and as a gargle. Russian soldiers historically used Black Walnut—thanks to its tannin content—to clean wounds and speed healing of external injuries and ulcers.
Black Walnut’s bioactive compounds have been studied for their ability to eliminate intestinal parasites during gastrointestinal infections. It is an ingredient in many antiparasitic and antifungal herbal blends, effective against various microorganisms, including Giardia, flatworms, hookworms, and roundworms.
In 2012, quinone-rich extracts from Black Walnut were evaluated for antimicrobial effects, with juglone showing a specific bactericidal activity against the Erwinia amylovora strain, suggesting its potential as a natural antibiotic alternative.
Another study published in Phytotherapy Research found that juglone significantly inhibits the activity of RNase H in HIV viruses. Because RNase H is a key enzyme in HIV replication (supporting and catalyzing the degradation of RNA in DNA/RNA hybrids formed after reverse transcription), inhibiting this enzyme can halt viral replication—demonstrating notable antiviral effects.
Tannins (polyphenolic compounds) in Black Walnut can reduce cholesterol levels in the blood, constrict sweat glands to reduce perspiration, and provide relief from diarrhea and excessive bleeding.
Traditional and Folk Medicine
Black Walnut hulls, kernels, leaves, and pericarp (fruit rind) are used in herbal medicine, primarily to detoxify the body, strengthen the immune system, stimulate brain function, improve appetite, lower cholesterol, ease atherosclerotic symptoms, and support cardiovascular health (with a significant effect on the arteries). Folk medicine recommends using the hulls for painful digestion, colic, heartburn, flatulence, bile stimulation, prevention of heart diseases, and externally for painful sores and stubborn acne.
Traditionally, Black Walnut hulls have also been used for the treatment of certain tumor conditions; North American herbalists recommend Black Walnut to help stabilize leukemia, as well as for syphilis, as a wash for skin disorders, or as a gargle for inflammation of the oral cavity or nasopharynx.
Active Compounds
Per 100 grams of Black Walnut hull, approximately 10 g are carbohydrates, fats account for about 59 g (mainly polyunsaturated fatty acids such as linoleic, oleic, palmitic, and stearic acids), and protein makes up 24 g. The remainder consists of vitamins B1, B2, B3, high amounts of B5 and B6, plus B9, B12, C, D, E, and K. Key bioactive components are juglone (a naphthoquinone derivative), plumbagin (a quinone pigment), and tannin (a polyphenol). It is also rich in manganese, phosphorus, magnesium, and zinc, and contains smaller amounts of calcium, iron, sodium, and potassium. About 4 grams is water content.
Traditional Dosage
Black Walnut is typically prepared as a decoction by mixing one tablespoon of the herb with 750 ml of cold water. Bring to a boil and simmer on low heat for up to 10 minutes. Remove from heat and divide the decoction into three servings to be consumed throughout the day.
