Walnut is the common name given to twenty species of deciduous trees in the genus Juglans, of which six species are native to the United States. The black walnut, Juglans nigra, which is native to Virginia, grows from Maine west to southern Michigan and south to Texas and Georgia.
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. 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.
Walnut nut husks are often used to create a rich yellow-brown to dark brown dye that is used for dyeing fabric and for other purposes. When picking walnuts, the husks should be handled wearing rubber gloves, to avoid dyeing one's fingers.
Wood
The Persian Walnut, and the Black Walnut and its allies, are important for their attractive timber, which (except in young trees) is hard, dense, tight-grained and polishes to a very smooth finish. The color ranges from creamy white in the sapwood to a dark chocolate color in the heartwood. When kiln-dried, walnut wood tends toward a dull brown color, but when air-dried can become a rich purplish-brown. Because of its color, hardness and grain it is a prized furniture and carving wood. Walnut burls are commonly used to create bowls and other turned pieces. The wood of the Butternut and related Asian species is of much lower value, softer, coarser, less strong and heavy, and paler in color.
Leaves
The leaves are alternate (occurring at different points along the twig), and pinnately compound. A compound leaf consists of many leaflets, which make up a single leaf versus a simple leaf, which has but one part. A leaf can be determined from a leaflet by locating a lateral bud at its base on the twig. An example of a simple leaf is a sugar maple leaf.Bark
The bark is black, thick and deeply furrowed. When scraped with a knife, it reveals a chocolate-covered sub-surface. The twigs are stout, greenish or orange-brown in color, and may be hairy or smooth. The pith (inner portion of the twig) is dark brown in color and is partitioned (chambered) when sliced with a knife.Fruit
The fruits (walnuts) occur singly or in groups of 2 or 3. They are spherical in shape and 2 inches or larger in diameter. The outer husk is yellow-green, but quickly darken and turn black when they fall to the ground. The inner nut has a very hard shell, is dark brown in color, deeply ridged and has a sweet tasting edible nut. Remember to wear rubber gloves when picking walnuts because the nuts will stain your hands and it is difficult to remove.Habitat
According to Dr. Royle Juglans regia extends from Greece and Asia Minor, over Lebanon and Persia, probably all along the Hindu-Kush to the Himalayas. It is abundant in Kashmir, and is found in Sirmore, Kumdon and Nepal. The walnuts imported into the plains of India are chiefly from Kashmir. Dr. Hooker states that in the Sikkim Himalaya, the Walnut inhabits the mountain slopes at an elevation of 4,000 to 7,000 feet. According to Pliny, it was introduced into Italy from Persia, and it is mentioned by Varro, who was born B.C. 116, as growing in Italy during his lifetime. There is no certain account of the time it was brought into this country. Some say 1562; but Gerard, writing about thirty years later, mentions the Walnut as being very common in the fields near common highways, and in orchards.Uses
NutsThe 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. 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.
Walnut nut husks are often used to create a rich yellow-brown to dark brown dye that is used for dyeing fabric and for other purposes. When picking walnuts, the husks should be handled wearing rubber gloves, to avoid dyeing one's fingers.
Wood
The Persian Walnut, and the Black Walnut and its allies, are important for their attractive timber, which (except in young trees) is hard, dense, tight-grained and polishes to a very smooth finish. The color ranges from creamy white in the sapwood to a dark chocolate color in the heartwood. When kiln-dried, walnut wood tends toward a dull brown color, but when air-dried can become a rich purplish-brown. Because of its color, hardness and grain it is a prized furniture and carving wood. Walnut burls are commonly used to create bowls and other turned pieces. The wood of the Butternut and related Asian species is of much lower value, softer, coarser, less strong and heavy, and paler in color.