Walnuts are an indigenous fruit species of California. Juglans californica is native to Southern California and the Central Valley, whereas Juglans hindsii is native to the northern parts. Franciscan Fathers first introduced the English walnut around the 1770s from South America to California. As of 1998, walnuts from California account for 99% of all walnuts grown in the United States, and for 38% of the world's production of walnuts.