Walnut is the name of a type of tree valued for its nuts and wood. Several species of walnut trees grow in the United States. Two of these are native to the East--the black walnut and the butternut, also called the white walnut. Another species, the English walnut or Persian walnut, was brought to the United States from southern Europe. It is grown commercially in California and Oregon. Black and English walnut trees provide high-quality wood for furniture.

English walnut trees produce walnuts that have the greatest commercial value. They are large, spreading trees that grow up to 100 feet (30 meters) tall. They have gray bark, large leaflets, and soft wood. They have been grown commercially in Europe since ancient times.

The English walnut tree bears clusters of small flowers called catkins. The flowers may be cross-pollinated or self-pollinated. After flowering, the tree produces walnuts. The nuts have thin shells and taste mild and sweet. They contain mostly fats and some proteins.

Growers typically plant English walnut trees at least 60 feet (18 meters) apart. But several varieties may be planted closer together. English walnut trees thrive in deep, well-drained soil. After the nuts ripen, they are shaken from the trees, hulled, and dried. The nuts are taken to packing houses and are sorted and sized. They may be packaged either in the shell or shelled. The poorer grades of nuts are used to make walnut oil.

Growers once left walnut shells that fell to the ground as waste. Today, the shells are collected and used in glues and plastics. They are also used to make solutions for cleaning and polishing metal surfaces.

The United States leads the world in the production of walnuts. Other major walnut-growing countries include China, Greece, and Turkey. The U.S. walnut industry is centered in the area around Stockton, Calif. In addition, several hardy varieties of English walnut trees are grown in the Midwest and the East. But growers usually do not plant large orchards of these varieties. English walnut trees do not grow well in the South.

Black walnut trees grow in forests from Massachusetts to Florida and west to Texas. They are hardy trees that are grown mainly for their lumber. The nuts also are harvested and sold. They have a distinctive and rich flavor, but their shell is hard and thick. They are usually shelled before they are sold. Growers have also developed a few thin-shelled varieties of these nuts.

Black walnut wood is dark purplish-brown, with a fine grain and luster. It is valuable for interior finishing, furniture, and gunstocks. This wood is becoming rare.

Scientific Classification. Walnuts belong to the walnut family, Juglandaceae. The scientific name for the English walnut is Juglans regia. The black walnut is J. nigra, and the butternut is J. cinerea.

Contributor: Richard A. Jaynes, Ph.D., Horticulturalist and Consultant, Broken Arrow Nursery.

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 See also:  BUTTERNUT