Walnut JuglansWalnut plants belong to the Juglans genus, and there are several species of walnut trees, with the most common one being Juglans regia, also known as the Persian walnut or English walnut. Walnut trees are deciduous trees that produce the nutritious and flavorful walnut nuts. They are native to regions of Central Asia, but they are now grown in temperate regions around the world for their nuts and timber.