Juglans nigra, the eastern American black walnut, is a species of deciduous tree in the walnut family, Juglandaceae, native to North America. It grows mostly in riparian zones, from southern Ontario, west to southeast South Dakota, south to Georgia, northern Florida and southwest to central Texas. Wild trees in the upper Ottawa Valley may be an isolated native population or may have derived from planted trees. Black walnut is an important tree commercially, as the wood is a deep brown color and easily worked. Walnut seeds (nuts) are cultivated for their distinctive and desirable taste. Walnut trees are grown both for lumber and food, and many cultivars have been developed for improved quality wood or nuts. Black walnut is susceptible to thousand cankers disease, which provoked a decline of walnut trees in some regions. Black walnut is anecdotally known for being allelopathic, which means that it releases chemicals from its roots and other tissues that may harm other organisms and give the tree a competitive advantage. There is not, however, solid scientific consensus that allelopathic chemicals in black walnut are the primary source of its competitive growth in an area. Description Odor Most parts of the tree including leaves, stems, and fruit husks have a very characteristic pungent or spicy odor. This odor is lacking in the nut itself. Trunk Height . Under forest competition, it develops a tall and straight trunk. When grown in an open area it has a short trunk and broad crown. Bark The bark is typically grey-black and deeply furrowed into thin ridges that gives the bark a diamond shaped pattern. Pith The pith of the twigs is chambered and light brown. Buds The buds are pale silky and covered in downy hairs. The terminal buds are ovate, and long, and slightly longer than broad, the lateral buds are smaller and superposed. Leaves The leaves are pinnately compound and alternately arranged on the stem. They are long, typically even-pinnate but there is heavy variation among leaves. The stems have 15–23 leaflets, when terminal leaf is included, with the largest leaflets located in the center, long and broad. The leaflets have a rounded base and a long pointed (acuminate) tip as well as having a serrated edge. The leaves are overall dark green in color and are typically hairy on the underside. Leaf scar The leaf scar has three prominent bundle scars and has a notch