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Persian Walnut
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Juglans regia (the Common walnut, Persian walnut, or English walnut), is the original walnut tree of the Old World. It is native in a region stretching from the Balkans eastward to the Himalayas and southwest China. The largest forests are in Kyrgyzstan, where trees occur in extensive, nearly pure walnut forests at 1,000–2,000 m altitude (Hemery 1998)—notably at Arslanbob in Jalal-Abad Province.
Juglans regia is a large deciduous tree attaining heights of 25–35 m, and a trunk up to 2 m diameter, commonly with a short trunk and broad crown, though taller and narrower in dense forest competition.
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Encyclopedia
Juglans regia (the Common walnut, Persian walnut, or English walnut), is the original walnut tree of the Old World. It is native in a region stretching from the Balkans eastward to the Himalayas and southwest China. The largest forests are in Kyrgyzstan, where trees occur in extensive, nearly pure walnut forests at 1,000–2,000 m altitude (Hemery 1998)—notably at Arslanbob in Jalal-Abad Province.
Juglans regia is a large deciduous tree attaining heights of 25–35 m, and a trunk up to 2 m diameter, commonly with a short trunk and broad crown, though taller and narrower in dense forest competition. It is a light-demanding species, requiring full sun to grow well.
The bark is smooth, olive-brown when young and silvery-grey on older branches, with scattered broad fissures with a rougher texture. Like all walnuts, the pith of the twigs contains air spaces, the chambered pith brownish in colour. The leaves are alternately arranged, 25-40 cm long, odd-pinnate with 5–9 leaflets, paired alternately with one terminal leaflet. The largest leaflets the three at the apex, 10–18 cm long and 6–8 cm broad; the basal pair of leaflets much smaller, 5–8 cm long, the margins of the leaflets entire. The male flowers are in drooping catkins 5–10 cm long, the female flowers terminal, in clusters of two to five, ripening in the autumn into a fruit with a green, semi-fleshy husk and a brown corrugated nut. The whole fruit, including the husk, falls in autumn; the seed is large, with a relatively thin shell, and edible, with a rich flavour.
Cultivation and uses
Juglans regia is grown extensively for nut, as an ornamental tree, and for wood.
The walnut was introduced into western and northern Europe very early, by Roman times or earlier, and to the Americas by the 17th century, by English colonists. Important nut-growing regions include France, Serbia, Greece, Bulgaria, and Romania in Europe, China in Asia, California in North America, and Chile in South America. Lately the crop has spread to another regions: New Zealand and southeast of Australia. It is cultivated extensively for its high-quality nuts, eaten both fresh and pressed for their richly flavoured oil; numerous cultivars have been selected for larger nuts with thinner shells.
The wood is of very high quality, and is used to make furniture and rifle stocks.
Walnut ink, made by boiling the whole fruit or letting it oxidize, is dark brown in color and darkens as it oxidizes. It can also be used to stain wood.
Nutritional value
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A study of ten cultivars of J. regia in Turkey showed significant variations in fatty acid content:
Etymology and other names
The scientific name Juglans is from Latin jovis glans, "Jupiter's acorn", and regia, "royal". Its common name, Persian walnut, indicates its origins in Persia in southwest Asia; 'walnut' derives from the Germanic wal- for "foreign", recognizing that it is not a nut native to Great Britain.
Other names include Walnut (which does not distinguish the tree from other species of Juglans), Common Walnut and English Walnut, the latter name possibly because English sailors were prominent in Juglans regia nut distribution at one time. In the Chinese language, the edible, cultivated walnut is called ?? (hú táo in Mandarin), which means literally "Hu peach," suggesting that the ancient Chinese associated the introduction of the tree into East Asia with the Hu barbarians of the regions north and northwest of China. In Mexico, it is called nogal de Castilla, suggesting that the Mexicans associate the introduction of the tree into Mexico with Spaniards from Castile
Folklore
In Skopelos, a Greek island in the Aegean Sea, local legend suggests that whoever plants a walnut tree will die as soon as the tree can "see" the sea. This has not been proven as fact, however it might take some time to find a local arborist willing to take on the job of planting a walnut tree. Most planting is done by field rats (subfamily Murinae).
In Flanders, the saying (in Dutch) goes "Boompje groot, plantertje dood", meaning "By the time the tree is big, the planter sure will be dead". The saying refers to the relatively slow growth rate of the tree.
Health aspects of walnuts
The walnut marketing industry has issued a press release interpreting a 2006 study published in the Journal of the American College of Cardiology to mean that eating walnuts after a meal high in saturated fats can reduce the damaging effects of such fats on blood vessels. Researchers from Barcelona's Hospital Clinic conducted a study on 24 adult participants, half of whom had normal cholesterol levels, and half of whom had moderately high levels of cholesterol. Each group was fed two high-fat meals of salami and cheese, eaten one week apart. During one meal, the researchers supplemented the food with five teaspoons of olive oil; the researchers added 40 g shelled walnuts to the other meal.
Tests after each meal showed that neither the olive oil nor the walnuts had any effect on inflammatory substances or lipid oxidation in the blood samples taken after the meals. However, the participants with moderately high cholesterol levels exhibited increased arterial wall movement after the meal containing walnuts and decreased movement after the meal containing olive oil. The participants who had normal cholesterol levels showed a much smaller effect on arterial movement.
Lead researcher Dr. Emilio Ros, who serves on the scientific advisory board of the California Walnut Commission, speculated that walnuts' protective effects could be because the nuts are high in antioxidants and ALA, an omega-3 fatty acid. Dr. Emilio Ros also noted that walnuts also contain arginine, which is an amino acid that the body uses to produce nitric oxide, which he stated was necessary for keeping blood vessels flexible.
Oral Walnut Leaves and Diabetes Mellitus
A tantalizing study has found that feeding walnut leaves to diabetic rats with induced insulin-dependent diabetes mellitus had the effects of reducing fasting blood sugar and of regenerating beta cells.
Alcoholic Walnut extract and Alzheimer's
A 2004 study by the (OMRDD) found that walnut extract was able to inhibit and defibrillize (break down) fibrillar amyloid beta protein - the principal component of amyloid plaques in the brains of patients with Alzheimer's. The study looked at the effect of walnut extract on amyloid beta protein fibrillization by Thioflavin T fluorescence spectroscopy and electron microscopy. Similarly, in a study done at Baldwin-Wallace College in Berea, Ohio it was found that two of its major components in walnuts, gallic and ellagic acid, act as "dual-inhibitors" of the enzyme acetylcholinesterase which, in association with amyloid-ß, inhibits protein aggregation, and will also inhibit the site of acetylcholinesterase responsible for the breakdown of acetylcholine.
These results suggest that walnuts may reduce the risk or delay the onset of Alzheimer's disease by maintaining amyloid-ß protein in the soluble form and prevent the breakdown of acetylcholine.
Walnuts in Chinese medicine
In Traditional Chinese Medicine, walnut seeds are primarily considered a kidney tonic. They are also considered beneficial to the brain, back, and skin, and to relieve constipation if it is caused by dehydration.
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