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  • Juglans nigra, the eastern black walnut, a species of flowering tree in the walnut family, Juglandaceae, is native to eastern 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. Isolated wild trees in the upper Ottawa Valley may be an isolated native population or may have derived from planted trees. The black walnut is a large deciduous tree attaining heights of 30–40 m. Under forest competition, it develops a tall, clear trunk; the open-grown form has a short trunk and broad crown. The bark is grey-black and deeply furrowed. The pith of the twigs contains air spaces. The leaves are alternate, 30–60 cm long, odd-pinnate with 15–23 leaflets, with the largest leaflets located in the center, 7–10 cm long and 2–3 cm broad. The male flowers are in drooping catkins 8–10 cm long, the female flowers are terminal, in clusters of two to five, ripening during the autumn into a fruit with a brownish-green, semifleshy husk and a brown, corrugated nut. The whole fruit, including the husk, falls in October; the seed is relatively small and very hard.

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