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Juglans regia - L.

Common Name Walnut, English walnut, Persian Walnut,
Family Juglandaceae
USDA hardiness 7-9
Known Hazards None known
Habitats Forests in the Himalayas, preferring a northerly aspect in the west but a southerly or westerly aspect in the east of the range[144].
Range E. Europe to N. Asia. More or less naturalized in S. Britain.
Edibility Rating    (4 of 5)
Other Uses    (4 of 5)
Weed Potential No
Medicinal Rating    (3 of 5)
Care (info)
Fully Hardy Moist Soil Full sun
Juglans regia Walnut, English walnut, Persian Walnut,


http://commons.wikimedia.org/wiki/File:Koeh-081.jpg
Juglans regia Walnut, English walnut, Persian Walnut,
http://commons.wikimedia.org/wiki/User:Rasbak

 

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Summary

Main Bloom Time: Early spring, Late spring, Mid spring. Form: Rounded.


Physical Characteristics

 icon of manicon of lolypop
Juglans regia is a deciduous Tree growing to 20 m (65ft) by 20 m (65ft) at a medium rate.
See above for USDA hardiness. It is hardy to UK zone 5 and is not frost tender. It is in flower in June, and the seeds ripen in October. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and is pollinated by Wind. The plant is self-fertile.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers moist soil.

UK Hardiness Map US Hardiness Map

Synonyms

Habitats

Woodland Garden Canopy;

Edible Uses

Edible Parts: Oil  Oil  Sap  Seed
Edible Uses: Oil  Oil  Sweetener  Tea

Seed - eaten raw or used in confections, cakes, ice cream etc[2, 5, 12, 34, 183]. A delicious flavour. The seed can also be ground into a meal and used as a flavouring in sweet and savoury dishes[183]. The unripe fruits are pickled in vinegar[183]. An edible oil is obtained from the seed[4, 7, 57, 183], it should not be stored for any length of time since it tends to go rancid quickly[7, 132]. The oil has a pleasant flavour and is used in salads or for cooking[183]. The sap is tapped in spring and used to make a sugar[117]. The finely ground shells are used in the stuffing of 'agnolotti' pasta[183]. They have also been used as adulterant of spices[269]. The dried green husks contain 2.5 - 5% ascorbic acid (vitamin C) - this can be extracted and used as a vitamin supplement[269]. The leaves are used as a tea[183].

References   More on Edible Uses

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.
Alterative  Anodyne  Antiinflammatory  Astringent  Bach  Blood purifier  Cancer  Depurative  
Detergent  Diuretic  Eczema  Laxative  Lithontripic  Miscellany  Pectoral  
Skin  Stimulant  Urinary  Vermifuge  Vitamin C

The walnut tree has a long history of medicinal use, being used in folk medicine to treat a wide range of complaints[269]. The leaves are alterative, anthelmintic, anti-inflammatory, astringent and depurative[9, 218]. They are used internally the treatment of constipation, chronic coughs, asthma, diarrhoea, dyspepsia etc[9]. The leaves are also used to treat skin ailments and purify the blood[9, 218]. They are considered to be specific in the treatment of strumous sores[240]. Male inflorescences are made into a broth and used in the treatment of coughs and vertigo[218]. The rind is anodyne and astringent[147]. It is used in the treatment of diarrhoea and anaemia[238]. The seeds are antilithic, diuretic and stimulant[218]. They are used internally in the treatment of low back pain, frequent urination, weakness of both legs, chronic cough, asthma, constipation due to dryness or anaemia and stones in the urinary tract[176]. Externally, they are made into a paste and applied as a poultice to areas of dermatitis and eczema[176]. The oil from the seed is anthelmintic[218]. It is also used in the treatment of menstrual problems and dry skin conditions[238]. The cotyledons are used in the treatment of cancer[218]. Walnut has a long history of folk use in the treatment of cancer, some extracts from the plant have shown anticancer activity[218]. The bark and root bark are anthelmintic, astringent and detergent[218, 240]. The plant is used in Bach flower remedies - the keywords for prescribing it are 'Oversensitive to ideas and influences' and 'The link-breaker'[209].

References   More on Medicinal Uses

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Other Uses

Dye  Herbicide  Miscellany  Oil  Oil  Paint  Polish  Repellent  Tannin  Teeth  Wood

A yellow dye is obtained from the green husks[4, 7, 100, 117]. It is green[148]. The green nuts (is this the same as the green husks?) and the leaves are also used[148]. The rind of unripe fruits is a good source of tannin[158]. A brown dye is obtained from the leaves and mature husks[4, 7, 48, 117, 168]. It does not require a mordant and turns black if prepared in an iron pot[168]. The dye is often used as a colouring and tonic for dark hair[238]. The leaves and the husks can be dried for later use[169]. A golden-brown dye is obtained from the catkins in early summer. It does not require a mordant[168]. A drying oil is obtained from the seed. It is used in soap making, paints, etc. It is not very stable and quickly goes rancid[7, 21, 34, 46]. The nuts can be used as a wood polish. Simply crack open the shell and rub the kernel into the wood to release the oils. Wipe off with a clean cloth[4, 6, K]. The dried fruit rind is used to paint doors, window frames etc[145] (it probably protects the wood due to its tannin content). The shells may be used as anti-skid agents for tyres, blasting grit, and in the preparation of activated carbon[269]. The leaves contain juglone, this has been shown to have pesticidal and herbicidal properties[218]. The crushed leaves are an insect repellent[46, 61]. Juglone is also secreted from the roots of the tree, it has an inhibitory effect on the growth of many other plants[201]. Bark of the tree and the fruit rind are dried and used as a tooth cleaner. They can also be used fresh[145, 158]. Wood - heavy, hard, durable, close grained, seasons and polishes well. A very valuable timber tree, it is used for furniture making, veneer etc[1, 4, 7, 46, 61, 158]. A dynamic accumulator gathering minerals or nutrients from the soil and storing them in a more bioavailable form - used as fertilizer or to improve mulch.

Special Uses

Carbon Farming  Dynamic accumulator  Food Forest  Scented Plants

References   More on Other Uses

Cultivation details

Global Crop  Management: Standard  Other Systems: Irreg. Intercrop  Other Systems: Strip intercrop  Staple Crop: Protein-oil

Landscape Uses:Aggressive surface roots possible, Specimen. Requires a deep well-drained loam[11] and a sunny position sheltered from strong winds. Prefers a slightly alkaline heavy loam but succeeds in most soils[1, 63]. The walnut tree is reported to tolerate an annual precipitation of 31 to 147cm, an annual temperature in the range of 7.0 to 21.1°C and a pH in the range of 4.5 to 8.2[269]. The dormant plant is very cold tolerant, tolerating temperatures down to about -27°C without serious damage, but the young spring growth is rather tender and can be damaged by late frosts[269]. Some late-leafing cultivars have been developed, these often avoid damage from spring frosts and can produce a better quality timber tree. The walnut tree is frequently cultivated for its edible seed in temperate zones of the world, there are many named varieties[63, 183]. Newer cultivars begin producing nuts in 5 - 6 years; by 7 - 8 years, they produce about 2.5 tons of nuts per hectare[269]. Orchards on relatively poor, unirrigated mountain soil report 1.5 - 2.25 tonnes per hectare, orchards in well cultivated valleys, 6.5 - 7.5 tonnes per hectare[269]. According to the Wealth of India, a fully grown individual can yield about 185 kg, but 37 kg is more likely[269]. Trees grow well in most areas of Britain but they often fail to fully ripen their fruits or their wood in our cooler and damper climate[63, 200], they prefer a more continental climate. There are some very fine trees in Cornwall[59]. Walnuts can produce large healthy trees in many parts of Britain, but seedling trees often do not fruit reliably. Some European varieties have been developed that succeed in colder areas[200]. Seedling trees are said to take from 6 to 15 years to come into fruit from seed[200], but these cultivars usually start cropping within 5 years. Plants produce a deep taproot and they are intolerant of root disturbance. Seedlings should be planted out into their permanent positions as soon as possible and given some protection for their first winter or two since they are somewhat tender when young. Flower initiation depends upon suitable conditions in the previous summer. The flowers and young growths can be destroyed by even short periods down to -2°c[63], but fortunately plants are usually late coming into leaf. Some cultivars are self-fertile, though it is generally best to grow at least two different cultivars to assist in cross-pollination. Any pruning should only be carried out in late summer to early autumn or when the plant is fully dormant otherwise wounds will bleed profusely and this will severely weaken the tree. Plants produce chemicals which can inhibit the growth of other plants. These chemicals are dissolved out of the leaves when it rains and are washed down to the ground below, reducing the growth of plants under the tree[18, 20, 159]. The roots also produce substances that are toxic to many plant species, especially apples (Malus species), members of the Ericaceae, Potentilla spp and the white pines (certain Pinus spp.)[200]. Trees have a dense canopy which tends to reduce plant growth below them[20]. All in all, not the best of companion trees, it is also suggested that the trees do not like growing together in clumps[37]. Trees are said to inhibit the growth of potatoes and tomatoes[18]. Hybridizes with J. nigra[149]. This species is notably susceptible to honey fungus[200]. The bruised leaves have a pleasant sweet though resinous smell[245]. Special Features: Not North American native, Inconspicuous flowers or blooms. The plant is heat tolerant in zones 7 through 1. (Plant Hardiness Zones show how well plants withstand cold winter temperatures. Plant Heat Zones show when plants would start suffering from the heat. The Plant Heat Zone map is based on the number of "heat days" experienced in a given area where the temperature climbs to over 86 degrees F (30°C). At this temperature, many plants begin to suffer physiological damage. Heat Zones range from 1 (no heat days) to 12 (210 or more heat days). For example Heat Zone. 11-1 indicates that the plant is heat tolerant in zones 11 through 1.) For polyculture design as well as the above-ground architecture (form - tree, shrub etc. and size shown above) information on the habit and root pattern is also useful and given here if available. The plant growth habit is a standard with a non-suckering single trunk [1-2].

Carbon Farming

  • Global Crop  These crops are already grown or traded around the world. The annual value of each is more than $1 billion US Examples include coconuts, almonds, and bananas.
  • Management: Standard  Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.
  • Other Systems: Irreg. Intercrop  Irregular intercropping systems are trees scattered throughout cropland.
  • Other Systems: Strip intercrop  Tree crops grown in rows with alternating annual crops.
  • Staple Crop: Protein-oil  (16+ percent protein, 16+ percent oil). Annuals include soybeans, peanuts, sunflower seeds. Perennials include seeds, beans, nuts, and fruits such as almond, Brazil nut, pistachio, walnut, hazel, and safou.

References   Carbon Farming Information and Carbon Sequestration Information

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Propagation

The seed is best sown as soon as it is ripe in individual deep pots in a cold frame[80]. You need to protect it from mice, birds, squirrels etc. The seed usually germinates in late winter or the spring. Plant out the seedlings into their permanent positions in early summer and give some protection from the cold for their first winter or two. The seed can also be stored in cool moist conditions (such s the salad compartment of a fridge) over the winter and sown in early spring but it may then require a period of cold stratification before it will germinate[78, 80, 113]. Named varieties are propagated by budding.

Other Names

If available other names are mentioned here

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Found In

Countries where the plant has been found are listed here if the information is available

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it’s worth checking.

Conservation Status

IUCN Red List of Threatened Plants Status :

Related Plants
Latin NameCommon NameHabitHeightHardinessGrowthSoilShadeMoistureEdibleMedicinalOther
Juglans ailanthifoliaJapanese WalnutTree20.0 4-8  LMHNM315
Juglans ailanthifolia cordiformisHeartseed WalnutTree20.0 4-8 MLMHNM414
Juglans californicaCalifornia Walnut, Southern California walnutTree6.0 7-10 MLMHNM212
Juglans cathayensisChinese WalnutTree20.0 4-8  LMHNM301
Juglans cinereaButternut - White Walnut, ButternutTree25.0 3-7 MLMHNM333
Juglans hindsiiHind's Black Walnut, Northern California walnut, Paradox hybrid walnutTree15.0 8-9 MLMHNM303
Juglans intermediaHind's Black Walnut, Northern California walnut, Paradox hybrid walnuHTree30.0 4-8  LMHNM301
Juglans majorArizona WalnutTree15.0 8-11 FLMHNM202
Juglans mandschuricaManchurian WalnutTree20.0 4-8  LMHNM314
Juglans microcarpaTexas Walnut, Little walnut, Stewart's little walnutTree10.0 5-9  LMHNM203
Juglans neotropicaAndean WalnutTree25.0 10-12 SLMHNM324
Juglans nigraBlack WalnutTree30.0 4-9 FLMHNM334
Juglans olanchanaOlancho walnut, Central American walnutTree45.0 10-12 MLMHSNMWe203
Juglans regia fallaxWalnutTree30.0 4-8  LMHNM301
Juglans regia kamaoniaWalnutTree30.0 4-8  LMHNM333
Juglans sinensis Tree20.0 -  LMHNM311
Juglans x bisbyiBuartnutTree20.0 4-8  LMHNM302

Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.

 

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Botanical References

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Readers comment

Jean C. Fisher   Fri May 21 23:22:27 2004

The "Royal Walnut" (Juglans regia) is a hybrid developed by Luther Burbank from the Eastern American Black Walnut and the Western American Black Walnut. The last remaining living tree out of the six that Burbank hybridized stands on the westernmost property line of what is left of Burbank's Gold Ridge Experiment Farm in Sebastopol, California, USA.

It was planted where stands by Burbank in the 1880s.

Link: Western Sonoma County Historical Society -- Gold Ridge Farm pages The online Burbank's Farm brochure has an entry for Burbank's "Royal Walnut".

Roddy Llewellyn   Wed Sep 5 2007

I have found two other named varieties in the region of the Correze in France, namely 'Marbeau' and 'Parisienne'. Question - are these varieties of Juglans regia?

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