The Black Walnut tree, Juglans nigra, is prized for its wood and shade. Black Walnut trees are a large, moderately growing, majestic tree. This deciduous tree makes a wonderful shade tree, and when planted for a wood plantation, makes a great long-term investment. This tree has moderate water requirements and is tolerant to drought. It has massive, upright spreading, open branches. The nuts are large and plump and crack out of the shell easily. The roots of the black walnut produce a substance known as juglone (5-hydroxy-alpha-napthaquinone). This biochemical is toxic to many plants such as the tomato, potato, black and blue berries, and other plants that may grow within a 50 to 60 foot radius of the trunk. Not all plants are sensitive to juglone and many trees, vines, shrubs, and flowers will thrive in close proximity to a Black Walnut tree.