Juglans regia, the Persian walnut, English walnut, Carpathian walnut, Madeira walnut, or especially in Great Britain, common walnut, is an Old World walnut tree species native to the region stretching from the Balkans eastward to the Himalayas and southwest China. It is widely cultivated across Europe. It is the origin of cultivated varieties which produce the edible walnut, consumed around the world. China is the major commercial producer of walnuts.