Walnuts
Walnuts (genus Juglans) are plants in the family Juglandaceae. The Latin name Juglans derives from Jovis glans, "Jupiter's acorn": figuratively, a nut fit for a god while the word walnut derives from Old English wealhhnutu, literally "foreign nut".
They are tall deciduous trees, with pinnate leaves.The 21 species in the genus range across the north temperate Old World from southeast Europe east to Japan, and more widely in the New World from southeast Canada west to California and south to Argentina.
The best-known member of the genus is the Persian Walnut (Juglans regia), native from the Balkans in southeast Europe (in Kyrgyzstan alone there are 230,700 ha of walnut-fruit forest), southwest & central Asia to the Himalaya and southwest China.
The Black Walnut (Juglans nigra) is a common species in its native eastern North America, and is also widely cultivated elsewhere. The nuts are edible, but have a smaller kernel and an extremely tough shell, and they are not widely grown for nut production.
Cultivation and uses
The two most commercially important species are J. regia for timber and nuts, and J. nigra for timber. Both species have similar cultivation requirements and are widely grown in temperate zones.
Walnuts are light-demanding species that benefit from protection from wind. Walnuts are also very hardy against water.
When grown for nuts care must be taken to select cultivars that are compatible for pollination purposes, although some cultivars are marketed as "self fertile" they will generally fruit better with a different pollination partner.
Persian Walnut nuts
The nuts of all the species are edible, but the walnuts commonly available in stores are from the Persian Walnut, the only species which has a large nut and thin shell. A horticultural form selected for thin nut shells and hardiness in temperate zones is sometimes known as the 'Carpathian' walnut. The nuts are rich in oil, and are widely eaten both fresh and in cookery. Walnut oil is expensive and consequently is used sparingly; most often in salad dressing. Walnuts are also an excellent source of omega-3 fatty acids, and have been shown as helpful in lowering cholesterol. They need to be kept dry and refrigerated to store well; in warm conditions they become rancid in a few weeks, particularly after shelling.
In some countries immature nuts in their husks are preserved in vinegar. In England these are called "pickled walnuts" and this is one of the major uses for fresh nuts from the small scale plantings. In Armenian cuisine, walnuts are preserved in sugar syrup and eaten whole. In Italy, liqueurs called Nocino and Nocello are flavoured with walnuts. In Georgia, walnuts are ground along with other ingredients to make walnut sauce.
Products
Pests