NL·0078Herbarium of the Nature Library
- Name
- Juglans regia
- Family
- Juglandaceae
- Native to
- Mountains of Central Asia, Iran, the Caucasus, the Himalaya and south-west China; cultivated across temperate Eurasia and the Americas
- Habitat
- Mountain walnut–fruit forests, Temperate river valleys, Orchards
Persian walnut
Juglans regia
Also calledAkhrot (Hindi/Urdu) · Gerdu (Persian) · Jawz (Arabic) · Hétao (Chinese) · Ceviz (Turkish) · Nogal / Nuez (Spanish) · Grecki orzech (Polish, 'Greek nut')
A majestic, long-lived nut tree from the mountains of Central Asia, prized for its oily nuts, its fine dark timber and the brown dye in its husks. Its roots and leaves release juglone, a chemical that suppresses many plants growing beneath it.
Juglans regia, known by various common names including the common walnut, English walnut, or Persian walnut amongst other names, is a species of walnut. It is native to Eurasia in at least southwest and central Asia and southeast Europe, but its exact natural area is obscure due to its long history of cultivation. Wikipedia
What it can do
- iLeaves, husks and roots contain juglone, an allelopathic compound that can inhibit some nearby plants, though less strongly than black walnut
- iiWild walnut–fruit forests of Kyrgyzstan's Arslanbob are among the largest natural walnut forests on Earth
- iiiWind-pollinated; male and female flowers on the same tree often mature at different times
- ivGreen husks stain skin and cloth dark brown
At the table
Eatennut kernel (fresh, dried, pressed for oil) · green immature nuts (pickled, or in nocino liqueur)
Kernels are safe; walnut is a common tree-nut allergen. Mouldy nuts may contain mycotoxins. Husk sap stains and can irritate skin.
In the medicine cabinet
| Tradition | Use |
|---|---|
| Traditional Chinese Medicine | Walnut kernel (hé táo rén) to tonify kidneys and lungs, ease cough and moisten the bowels |
| European herbal medicine | Leaf decoction (Commission E) for mild skin inflammation and excess sweating |
| Doctrine of Signatures | The brain-like kernel was thought to strengthen the head and brain |
Weight of evidence
Moderate. Some clinical trials with promising but limited or mixed results.
Active compounds
α-linolenic acid (omega-3), juglone (husk, leaves), ellagitannins, melatonin
Fruit & seed
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Fruit
Drupe-like nut (tryma)
Ripens: Autumn
Round fruit 4–6 cm with a smooth, green, aromatic husk that blackens and splits, releasing a wrinkled, two-halved woody shell.
Seed
Nut 3–5 cm
Brain-like, wrinkled, two-lobed kernel, cream-coloured inside with a thin papery light-brown skin, about 3–4 cm across, held inside a ridged tan woody shell
- Dispersal
- Rodents, crows and jays cache and forget nuts
- Germination
- Cold-stratify in moist sand 90–120 days (or sow outdoors in autumn) 5 cm deep; protect from squirrels
Photographs from Wikimedia Commons under open licences; hover for the photographer, click for the file.
How to grow it
Hardiness (USDA zones)
USDA 5–9 (Carpathian strains to 4). Survives winters down to about -29 °C.
- Light
- Full sun
- Water
- Moderate; deep watering in dry summers
- Soil
- Deep, fertile, well-drained loam, pH 6–7.5
- Propagation
- Grafting named cultivars (e.g. 'Chandler', 'Franquette', 'Broadview'); seed
- To harvest
- 4–6 years from a grafted tree; 8–12 from seed
- Climates
- Temperate, Continental, Mediterranean
- 1Choose a late-leafing variety where spring frosts occur, and plant where its 15–20 m canopy and juglone will not affect vegetable beds.
- 2Plant in winter in deep soil; walnuts form long taproots and resent transplanting.
- 3Water young trees deeply in dry spells and keep grass away from the trunk.
- 4Prune only in late summer (bleeding sap in spring weakens the tree), removing low and crossing branches.
- 5Gather nuts as they fall, remove husks promptly (wear gloves), and dry in shade until the kernel snaps crisply.
Can it grow where you are?
Where it lives
Recorded sightings
—
geo-referenced records in GBIF, from museums, herbaria and field observers.
Native range
Mountains of Central Asia, Iran, the Caucasus, the Himalaya and south-west China; cultivated across temperate Eurasia and the Americas
Drag the globe to turn it. Dots are where records exist, not a range map; darker means more records.
In the old herbals & bestiaries
Woodcuts and engravings matched from the Source Library’s scanned books by name. Plates marked “relative” show a close kin rather than this exact species. Click a plate to read the page it came from, with translation.
Notable Commentaries on the History of Plants
Leonhart Fuchs · 1549 · p.411
Commentaries on the Six Books of Pedanius Dioscorides on Medical Matter
Pietro Andrea Mattioli · 1565 · p.452
Commentaries on the Six Books of Dioscorides on Medical Matter
Pietro Andrea Mattioli · 1563 · p.268
Compendium of Materia Medica
李時珍 · 1596 · p.46
A voyage to the islands Madera Barbados Jamaica Vol. 1
Hans Sloane · 1707 · p.521
Herbarium Portatile, Oder Behendes Kräuter- und Gewächs-Buch: Darinn nicht allein 1363. so wol Einheimische als Außländndische Kräuter mit Lateinisch und Deutscher Benennung abgebildet, sondern auch die meisten, so in der Medicin gebräuchlich, kürtzlich erkläret werden
Panckow, Thomas · 1656 · p.347
In the stacks
Searching the stacks…
Every page naming Juglans regia in the Biodiversity Heritage Library →
Marginalia
The Romans called the walnut 'Jovis glans', acorn of Jupiter, which gave the genus name Juglans. Walnuts travelled from Persia to Greece and Rome, and Carpathian, Kashmiri and Xinjiang walnuts remain famed regional strains.
Curiosity
The English word 'walnut' means 'foreign nut', from Old English wealh-hnutu.
Kinship
Fact-checked: 2 corrections made to this sheet. Photographs: iNaturalist contributors under the licences shown. Records: GBIF.org. Historical plates: Source Library (CC BY-SA 4.0; originals public domain). Summary text: Nature Library editors and Wikipedia (CC BY-SA). Medicinal and edibility notes are historical and educational, not advice. iNaturalist taxon 63935.