Walnut are deciduous trees of the genus Juglans, including the black walnut, Juglans nigra, white walnut or butternut, Juglans cinerea, and the English or Persian walnut, Juglans regia. The leaves are large and compound. The flowers are of two kinds — staminate flowers in dense catkins, and pistillate flowers in clusters — and both are found on the same tree. The fruit of the walnut tree is an important crop, and the hard-shelled nuts are used as a food rich in oil. A brown dye is obtained from the husk surrounding the nut of the black wal­nut, and the bark yields a substance for tanning. Walnut wood is very valuable due to its durability and rich brown color. It is used for fine furniture, woodwork, and steering wheels. The black walnut is native to North America and is characterized by darker wood, a harder shell, and a distinctive flavor of the nuts. The English walnut is native to Europe but is extensively cultivated in the state of California. These softer shelled nuts are usually bleached for commercial purposes. In some forms the young green. fruit is pickled before the shell develops.