River Birch
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| River Birch Conservation status: Secure | ||||||||||||||||
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 River birch with male catkins, Johnsonville, South Carolina | ||||||||||||||||
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River Birch (Betula nigra) is a common small birch native in flood plains or swamps in the eastern United States from New Hampshire west to southern Minnesota, and south to northern Florida and east Texas.
It is a small deciduous tree growing to about 25 m tall at most. The bark is very variable, usually dark gray-brown to pinkish-brown and thickly scaly, but in some individuals, smooth and creamy pinkish-white, exfoliating in curly papery sheets. The leaves are alternate, ovate, 5-12 cm long and 4-9 cm broad, with a serrated margin. The flowers are wind-pollinated catkins 3-6 cm long, the male catkins pendulous, the female catkins erect. The fruit is unusual among birches in maturing in late spring; it is composed of numerous tiny winged seeds packed between the catkin bracts.
Cultivation and uses
While its native habitat is wet ground, it will grow on higher land, and its bark is quite distinctive, making it a favored ornamental tree for landscape use. A number of cultivars with much whiter bark than the normal wild type have been selected for garden planting, including 'Heritage' and 'Dura-heat'; these are notable as the only white-barked birches resistant to the bronze birch borer Agrilus anxius in warm areas of the southeastern US.
Native Americans used the boiled sap as a sweetener similar to maple syrup, and the inner bark as a survival food. It is usually too contorted and knotty to be of value as a timber tree.
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