Juglans californica shell that is difficult to remove. The Chumash Indians of the Channel Islands of California and Ventura County eat the nuts; however, they are not grown commercially for this purpose. "Juglans californica" is cultivated throughout California to support the walnut industry, used as a rootstock in English walnut orchards. It is also cultivated as an ornamental tree where it is planted in California native plant, xeriscape, and wildlife habitat gardens and natural landscaping in California, and in Hawaii. Some authorities (e.g. the California Native Plant Society) combine this species with "J. hindsii". On the other hand, a 2007 molecular analysis
Castanea sativa the plant can’t pollinate itself, making cross-pollination necessary. Some cultivars only produce one large nut per cupule, while others produce up to three nuts. The nut itself is composed of two skins: an external, shiny brown part, and an internal skin adhering to the fruit. Inside, there is an edible, creamy-white part developed from the cotyledon. The tree requires a mild climate and adequate moisture for good growth and a good nut harvest. Its year-growth (but not the rest of the tree) is sensitive to late spring and early autumn frosts, and is intolerant of lime. Under forest conditions, it