Juglans regia
L.
Walnut, English walnut, Persian Walnut
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(c) Ed Alverson, some rights reserved (CC BY), uploaded by Ed Alverson
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(c) Ahmed Mujčinović, some rights reserved (CC BY-NC-SA), uploaded by Ahmed Mujčinović
Description
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. It is noted for attracting wildlife. 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.
Edible Uses
Tea. Seed - eaten raw or used in confections, cakes, ice cream etc. A delicious flavour. The seed can also be ground into a meal and used as a flavouring in sweet and savoury dishes. The unripe fruits are pickled in vinegar. An edible oil is obtained from the seed, it should not be stored for any length of time since it tends to go rancid quickly. The oil has a pleasant flavour and is used in salads or for cooking. The sap is tapped in spring and used to make a sugar. The finely ground shells are used in the stuffing of 'agnolotti' pasta. They have also been used as adulterant of spices. The dried green husks contain 2.5 - 5% ascorbic acid (vitamin C) - this can be extracted and used as a vitamin supplement. The leaves are used as a tea.
Medicinal Uses
Alterative Anodyne Antiinflammatory Astringent Bach Blood purifier Cancer Depurative Detergent Diuretic Eczema Laxative Lithontripic Miscellany Pectoral Skin Stimulant Urinary Vermifuge Vitamin CThe walnut tree has a long history of medicinal use, being used in folk medicine to treat a wide range of complaints. The leaves are alterative, anthelmintic, anti-inflammatory, astringent and depurative. They are used internally the treatment of constipation, chronic coughs, asthma, diarrhoea, dyspepsia etc. The leaves are also used to treat skin ailments and purify the blood. They are considered to be specific in the treatment of strumous sores. Male inflorescences are made into a broth and used in the treatment of coughs and vertigo. The rind is anodyne and astringent. It is used in the treatment of diarrhoea and anaemia. The seeds are antilithic, diuretic and stimulant. 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. Externally, they are made into a paste and applied as a poultice to areas of dermatitis and eczema. The oil from the seed is anthelmintic. It is also used in the treatment of menstrual problems and dry skin conditions. The cotyledons are used in the treatment of cancer. Walnut has a long history of folk use in the treatment of cancer, some extracts from the plant have shown anticancer activity. The bark and root bark are anthelmintic, astringent and detergent. The plant is used in Bach flower remedies - the keywords for prescribing it are 'Oversensitive to ideas and influences' and 'The link-breaker'.
Distribution
E. Europe to N. Asia. More or less naturalized in S. Britain.
Where It Grows
TEMPERATE ASIA: Azerbaijan, Iran (north & west), Iraq (north), Tajikistan, Turkey, Turkmenistan,Afghanistan. TROPICAL ASIA: Pakistan (north), EUROPE: Czech Republic, Slovakia, Bulgaria, Bosnia and Herzegovina, Greece, Croatia, North Macedonia, Montenegro, Serbia, Slovenia,
Cultivation
Requires a deep well-drained loam and a sunny position sheltered from strong winds. Prefers a slightly alkaline heavy loam but succeeds in most soils. 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. 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. 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. Newer cultivars begin producing nuts in 5 - 6 years; by 7 - 8 years, they produce about 2.5 tons of nuts per hectare. 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. According to the Wealth of India, a fully grown individual can yield about 185 kg, but 37 kg is more likely. 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, they prefer a more continental climate. There are some very fine trees in Cornwall. 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. Seedling trees are said to take from 6 to 15 years to come into fruit from seed, 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, 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. 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.). Trees have a dense canopy which tends to reduce plant growth below them. All in all, not the best of companion trees, it is also suggested that the trees do not like growing together in clumps. Trees are said to inhibit the growth of potatoes and tomatoes. Hybridizes with J. nigra. This species is notably susceptible to honey fungus. The bruised leaves have a pleasant sweet though resinous smell. Walnuts are usually harvested in autumn when the husks begin to split and turn brown. Walnuts generally flower in spring producing long catkins for male flowers and clusters for female flowers. Walnuts are moderate to fast-growing trees, typically reaching maturity in about 10 to 15 years, depending on the species and growing conditions.
Propagation
The seed is best sown as soon as it is ripe in individual deep pots in a cold frame. 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. Named varieties are propagated by budding.
Other Uses
Dye Herbicide Miscellany Oil Oil Paint Polish Repellent Tannin Teeth Wood. Juglans species can be used in agroforestry for shade and as a nitrogen-fixing tree. They also provide valuable timber and can enhance biodiversity in mixed plantings. A yellow dye is obtained from the green husks. It is green. The green nuts (is this the same as the green husks?) and the leaves are also used. The rind of unripe fruits is a good source of tannin. A brown dye is obtained from the leaves and mature husks. It does not require a mordant and turns black if prepared in an iron pot. The dye is often used as a colouring and tonic for dark hair. The leaves and the husks can be dried for later use. A golden-brown dye is obtained from the catkins in early summer. It does not require a mordant. 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. 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. The dried fruit rind is used to paint doors, window frames etc (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. The leaves contain juglone, this has been shown to have pesticidal and herbicidal properties. The crushed leaves are an insect repellent. Juglone is also secreted from the roots of the tree, it has an inhibitory effect on the growth of many other plants. Bark of the tree and the fruit rind are dried and used as a tooth cleaner. They can also be used fresh. Wood - heavy, hard, durable, close grained, seasons and polishes well. A very valuable timber tree, it is used for furniture making, veneer etc. 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.
