The so-called "English" walnut originated in Persia, where it throve for many centuries before it was carried to Europe—to England, Germany, France, Spain and Italy—different varieties adapting themselves to each country. The name "walnut" is of German origin, meaning "foreign nut." The Greeks called it "the Royal nut," and the Romans, "Jupiter's Acorn," and "Jove's Nut," the gods having been supposed to subsist on it.

The great age and size to which the walnut tree will attain has been demonstrated in these European countries: one tree in Norfolk, England, 100 years old, 90 feet high, and with a spread of 120 feet, yields 54,000 nuts a season; another tree, 300 years old, 55 feet high, and having a spread of 125 feet, yields 1,500 pounds each season. In Crimea there is a notable walnut tree 1,000 years old that yields in the neighborhood of 100,000 nuts annually. It is the property of five Tartar families, who subsist largely on its fruit.

In European countries walnuts come into bearing from the sixteenth to the twenty-fourth year; in Oregon, from the eighth to the tenth year; grafted trees, sixth year.

The first walnut trees were introduced into America a century ago by Spanish friars, who planted them in Southern California. It was not until comparatively recent years that the hardier varieties from France, adapted to commercial use, were planted in California and later in Oregon. They were also tried in other localities, but without success.

Since the prolific productiveness of the English walnut on the Pacific Coast has been assured, many commercial groves have been set out.