Juglans regia
Phanerophyte
Νative to the region stretching from the Balkans eastward to the Himalayas and southwest China
Woodlands and scrub
Phanerophyte
Νative to the region stretching from the Balkans eastward to the Himalayas and southwest China
Woodlands and scrub
Phanerophyte
Νative to the region stretching from the Balkans eastward to the Himalayas and southwest China
Woodlands and scrub
Deciduous tree up to 25 m tall. Young shoots tomentose. Leaves impa¬ripinnate, 17-40 cm long; leaflets 5-9, softly tomentose, opposite to sub-opposite, 7-20 cm long, 3-8 cm broad, ovate to elliptic-ovate, acute to acuminate, glab¬rescent to pubescent on nerves beneath; petiolule 2-4 mm long. Male catkins 6-12 cm long, lateral; bract c. 2 mm long; bracteoles 2, c. 3 nun long, ovate to obovate, pubescent; tepals 4, ovate, c. 2 mm long; stamens 10-20, subsessile; anthers 2 mm long, irregularly apiculate, basifixed, dehiscing longitudinally. Female flowers 1-3, terminal on short spikes; involucral tube of fused bract and bracteoles, c. 3.5 mm long, tomentose, glandular, obscurely 4-toothed and irregular at the margin; tepals 4, linear, 2.5-4 mm long, alternating with the teeth; margin sparsely pubescent; ovary c. 3.5 mm long, ovoid, inferior; style c. 2 mm long; stigmas 2, recurved, plumose to fimbriate, exserted. Drupe up to 5 cm long, ovoid to subglobose; epicarp green, glandular; endocarp 2-valved; seed 2 to 4-lobed at the base.
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Major Threats
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Source | http://www.iucnredlist.org/apps/redlist/details/63495 |
Trees to 25 m tall. Leaves 25-30 cm; petiole 5-7 cm; petiole and rachis glabrescent, without glandular hairs; leaflets (3 or)5-9, entire on mature trees, sometimes obscurely serrulate on young plants; lateral leaflets subsessile or petiolule 1-2 mm, blade elliptic-ovate to long elliptic, 6-15 × 3-6 cm, abaxially glabrous except for tufts of hairs in vein axils, without glandular hairs, base oblique, subrounded, apex obtuse or acute to shortly acuminate; terminal petiolule 2.5-6 cm. Male spike 5-10(-15) cm. Stamens 6-30(-40). Fruiting spike usually with 1-3(-38) nuts. Nuts subglobose, 4-6 cm; husk glabrous, irregularly dehiscent; shell thick except in commercial varieties, wrinkled. Fl. Apr-May, fr. Oct. 2n = 32.
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A walnut is an edible seed of any tree of the genus Juglans, especially the Persian or English walnut, Juglans regia. Broken nutmeats of the eastern black walnut from the tree Juglans nigra are also commercially available in small quantities, as are foods prepared with butternut nutmeats from Juglans cinerea.
Walnut seeds are a high density source of nutrients, particularly proteins and essential fatty acids. Walnuts, like other tree nuts, must be processed and stored properly. Poor storage makes walnuts susceptible to insect and fungal mold infestations; the latter produces aflatoxin - a potent carcinogen. A mold infested walnut seed batch should not be screened and then consumed; the entire batch should be discarded.[1]
Walnuts are rounded, single-seeded stone fruits of the walnut tree. The walnut fruit is enclosed in a green, leathery, fleshy husk. This husk is inedible. After harvest, the removal of the husk reveals the wrinkly walnut shell, which is in two halves. This shell is hard and encloses the kernel, which is also made up of two halves separated by a partition. The seed kernels - commonly available as shelled walnuts - are enclosed in a brown seed coat which contains antioxidants. The antioxidants protect the oil-rich seed from atmospheric oxygen so preventing rancidity.[1]
The two most common major species of walnuts are grown for their seeds — the Persian or English Walnut and the Black Walnut. The English Walnut (J. regia) originated in Persia, and the Black Walnut (J. nigra) is native to eastern North America. The Black walnut is of high flavor, but due to its hard shell and poor hulling characteristics it is not grown commercially for nut production. The commercially produced walnut varieties are nearly all hybrids of the English walnut.[2]
Other species include J. californica, the California Black Walnut (often used as a root stock for commercial breeding of J. regia), J. cinerea (butternuts), and J. major, the Arizona Walnut.
Walnuts are late to bear leaves, typically not until more than halfway through the spring. They also secrete chemicals into the soil to prevent competing vegetation from growing. Because of this, flowers or vegetable gardens should not be planted too close to them.
The husks of walnut contains a juice that will readily stain anything it comes into contact with. It has been used as a dye for cloth.
Contents |
The worldwide production of walnut seeds has been increasing rapidly in recent years, with most increase coming from Asia. The world produced a total of 2.55 million metric tonnes of walnut seeds in 2010; China was the world's largest producer of walnut seeds, with a total harvest of 1.06 million metric tonnes.[3] The other major producers of walnut seeds were (in the order of decreasing harvest): United States, Iran, Turkey, Ukraine, Mexico, Romania, India, France and Chile.
The average worldwide walnut seed yield was about 3 metric tonnes per hectare, in 2010. Among the major producers, eastern European countries have the highest yield. According to the FAO, the most productive walnut seed farms in 2010 were in Romania, with yields above 23 metric tonnes per hectare.[4]
The United States is the world's largest exporter of walnut seeds. The Sacramento and San Joaquin valleys of California produce 99 percent of the nation’s commercial English walnut seeds.
The ideal temperature for longest possible storage of walnut seeds is in the -3 to 0 oC and low humidity - for industrial and home storage. However, such refrigeration technologies are unavailable in developing countries where walnuts are produced in large quantities; there, walnut seeds are best stored below 25 oC and low humidity. Temperatures above 30 oC, and humidities above 70 percent can lead to rapid and high spoilage losses. Above 75 percent humidity threshold, fungal molds that release dangerous aflatoxin can form.[1][5]
Freshly harvested raw walnut seeds with water content between 2 to 8 percent offer the best color, flavor and nutrient density.
Persian or English walnut, Juglans regia | |
Nutritional value per serving | |
---|---|
Serving size | 100 grams |
Energy | 2,738 kJ (654 kcal) |
Carbohydrates | 13.71 |
- Starch | 0.06 |
- Sugars | 2.61 |
- Lactose | 0 |
- Dietary fiber | 6.7 |
Fat | 65.21 |
- saturated | 6.126 |
- monounsaturated | 8.933 |
- polyunsaturated | 47.174 |
Protein | 15.23 |
Water | 4.07 |
Alcohol | 0 |
Caffeine | 0 |
Vitamin A equiv. | 1 μg (0%) |
Vitamin A | 20 IU |
- beta-carotene | 12 μg (0%) |
- lutein and zeaxanthin | 9 μg |
Thiamine (vit. B1) | 0.341 mg (30%) |
Riboflavin (vit. B2) | 0.15 mg (13%) |
Niacin (vit. B3) | 1.125 mg (8%) |
Pantothenic acid (B5) | 0.570 mg (11%) |
Vitamin B6 | 0.537 mg (41%) |
Folate (vit. B9) | 98 μg (25%) |
Vitamin B12 | 0 μg (0%) |
Vitamin C | 1.3 mg (2%) |
Vitamin D | 0 μg (0%) |
Vitamin D | 0 IU (0%) |
Vitamin E | 0.7 mg (5%) |
Vitamin K | 2.7 μg (3%) |
Calcium | 98 mg (10%) |
Iron | 2.91 mg (22%) |
Magnesium | 158 mg (45%) |
Manganese | 3.414 mg (163%) |
Phosphorus | 346 mg (49%) |
Potassium | 441 mg (9%) |
Sodium | 2 mg (0%) |
Zinc | 3.09 mg (33%) |
Percentages are relative to US recommendations for adults. Source: USDA Nutrient Database |
Walnuts are one of the several high nutrient density foods. 100 grams of walnuts contain 15.2 gram protein, 65.2 gram fat, and 6.7 gram dietary fiber. The protein in walnuts provides many essential amino acids.
While English walnut is the predominant commercially distributed nut because of the ease of its processing, its nutrient density and profile is significantly different from black walnut. The table below compares some of the major nutrients between English and Black walnuts.
Nutrient (per 100 gram) | English walnut seed | Black walnut seed |
---|---|---|
Carbohydrates (g) | 13.7 | 9.9 |
Protein (g) | 15.2 | 24.1 |
Unsaturated fatty acids (g) | 56.1 | 50.1 |
Poly to mono unsaturated fatty acids ratio |
47:9 | 35:15 |
Fiber (g) | 6.7 | 6.8 |
Calcium (mg) | 98 | 61 |
Iron (mg) | 2.9 | 3.1 |
Zinc (mg) | 3.1 | 3.4 |
Vitamin B-6 (mg) | 0.54 | 0.58 |
Unlike most nuts that are high in monounsaturated fatty acids, walnuts are composed largely of polyunsaturated fatty acids (47.2 grams), particularly alpha-linolenic acid (18:3n - 3; 9.1 gram) and linoleic acid (18:2n - 6; 38.1 gram). The beneficial effects of this unique fatty acid profile has been a subject of many studies and discussions. Banel and Hu concluded in 2009 that while walnut-enhanced diets are promising in short term studies, longer term studies are needed to ascertain better insights.[7]
Raw walnuts contain glyceryl triacylates of the n-3 fatty acid alpha-linolenic acid (ALA),[8] which is not as effective in humans as long-chain n-3 fatty acids,[9] and (mostly insoluble) antioxidants.[10][11][12][13][14] Roasting reduces antioxidant quality.[15] In 2010, a report[citation needed] published in the Journal of the American College of Nutrition said that walnuts and walnut oil improve reaction to stress.[16]
A study has suggested that consumption of walnuts increases fat oxidation and reduces carbohydrate oxidation without affecting total consumption, suggesting that walnut consumption may improve the use of body fat in overweight adults.[17] Walnuts have been shown to decrease the endothelial dysfunction associated with a high-fat meal.[18] Aged rats fed diets containing 2% to 6% walnuts showed reversal of age-associated motor and cognitive function, but a 9% walnut diet impaired performance, suggesting a J curve.[19]
On October 11, 2006, ScienceDaily published a report[20] which stated "New research shows that consuming a handful of raw walnuts along with meals high in saturated fat appears to limit the ability of the harmful fat to damage arteries," and attributed the result to a 2006 article in the Journal of the American College of Cardiology. The lead researcher, Emilio Ros, MD, PhD, was quoted as saying "People would get the wrong message if they think that they can continue eating unhealthy fats provided they add walnuts to their meals."[20] Funding for the study was provided by the California Walnut Commission, an industry marketing agency.[20]
A 2012 study showed that eating walnuts improved sperm quality in healthy young men.[21][22]
Scientists are not yet certain whether walnuts act as a cancer chemopreventive agent, an effect which may be a result of the fruit's high phenolic content, antioxidant activity, and potent in vitro antiproliferative activity.[23]
Compared to certain other nuts, such as almonds, peanuts and hazelnuts, walnuts (especially in their raw form) contain the highest total level of antioxidants, including both free antioxidants and antioxidants bound to fiber.[11]
To remove the husk from kernel can lead to hand staining. Walnut hulls contain phenolics that stain hands and can cause skin irritation. Seven phenolic compounds (ferulic acid, vanillic acid, coumaric acid, syringic acid, myricetin, juglone[24] and regiolone[25]) have been identified in walnut husks by using reverse phase-high performance liquid chromatography or crystallography.
Walnuts also contain the ellagitannin pedunculagin.[26]
(−)-Regiolone has been isolated with juglone, betulinic acid and sitosterol from the stem-bark of J. regia.[27]
In China, pairs of walnuts have traditionally been rotated and played with in the palm of the hand, both as a means to stimulate blood circulation and as a status symbol. Pairs of large, old and symmetrically shaped walnuts are valued highly and have recently been used as an investment, with some of them fetching tens of thousands of dollars.[28] Pairs of walnuts are also sometimes sold still in their green skin, as a form of gambling known as du he tao.[29]
Etymologically, the word walnut derives from the Germanic wal- and Old English wealhhnutu, literally "foreign nut", wealh meaning "foreign" (wealh is akin to the terms Welsh and Vlach; see Walha).[30]
In certain parts of the world, walnuts are locally known as Gerdoo,walnüsse, noix, nuéz, noz, nuc, ceviz, orah (орах), enkuyz (ընկոյզ), akharōṭ (अखरोट), kurumi (胡桃), hétáo (核桃), hodu (호두).
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Source | http://en.wikipedia.org/w/index.php?title=Walnut&oldid=538246417 |
Habit: Tree
The English or Persian walnut is found wild and cultivated in the Himalayas from 1000—3300 m alt. s. m. Ssp. fallax (Dode) Popov in Bull. App. Bot. 22, 3:204. 1929 (Juglans fallax Dode in Bull. Soc. Dendr. Fr. 89. 1906) is probably the form that occurs here. Valued for its wood and edible fruit; the wood is excellent for furniture, carving and for gun stocks; the bark is good for the gums and in the local market it is sold under the name of ‘dandasa’. It is also used as a vermi¬fuge and for staining; the leaves are used as fodder. The seed yields an oil used in cooking. The ‘kaghzi’ variety of walnut (Juglans doucloxiana of Dode) is valued for its thin shelled edible fruit.
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Juglans duclouxiana Dode; J. fallax Dode; J. kamaonia (C. de Candolle) Dode; J. orientis Dode; J. regia var. sinensis C. de Candolle; J. sinensis (C. de Candolle) Dode.
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Commonly cultivated in China from 23-42° N for its edible, oily nuts and hard, fine grained wood. Juglans regia has a very long history of cultivation in China and elsewhere; as a result, there are many cultivars, including five Chinese taxa that L.-A. Dode (Bull. Soc. Dendrol. France 2: 67-98. 1906), recognized on the basis of differences in shell thickness, size, etc.
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Type collection for Juglans orientis Dode
Catalog Number: US 39085
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Card file verified by examination of alleged type specimen
Preparation: Pressed specimen
Collector(s): S. Tschonoski
Year Collected: 1864
Locality: Nippon, Senano [Shinano Prov.], Honshu, Nagano, Japan, Asia-Temperate
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Rights holder/Author | This image was obtained from the Smithsonian Institution. Unless otherwise noted, this image or its contents may be protected by international copyright laws. |
Source | http://collections.mnh.si.edu/search/botany/?irn=2112266 |
Type fragment for Juglans duclouxiana Dode
Catalog Number: US 457889
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Card file verified by examination of alleged type specimen
Preparation: Pressed specimen
Collector(s): A. Henry
Locality: Mengtze [Meng-tsze], Yunnan, China, Asia-Temperate
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Rights holder/Author | This image was obtained from the Smithsonian Institution. Unless otherwise noted, this image or its contents may be protected by international copyright laws. |
Source | http://collections.mnh.si.edu/search/botany/?irn=2092743 |