Betula nigra (black birch, river birch, water birch) is a species of birch native to the Eastern United States from New Hampshire west to southern Minnesota, and south to northern Florida and west to Texas. It is one of the few heat-tolerant birches in a family of mostly cold-weather trees which do not thrive in USDA Zone 6 and up. B. nigra commonly occurs in flood plains and/or swamps.^[1] It is a deciduoustree growing to 25–30 meters (82–98 ft) with a trunk 50 to 150 centimeters (20 to 59 in) in diameter, often with multiple trunks. The bark is variable, usually dark gray-brown to pinkish-brown and scaly, but in some individuals, smooth and creamy pinkish-white, exfoliating in curly papery sheets. The twigs are glabrous or thinly hairy. The leaves are alternate, ovate, 4–8 centimeters (1.6–3.1 in) long and 3–6 centimeters (1.2–2.4 in) broad, with a serrated margin and five to twelve pairs of veins. The flowers are wind-pollinated catkins 3–6 centimeters (1.2–2.4 in) 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.^[1][2]

Cultivation and uses[edit]

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 borerAgrilus anxius in warm areas of the southeastern United States of America.^[3]

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.^[3]

Gallery[edit]

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  New leaves on a nearly matured River Birch
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  At Skyfields Arboretum

References[edit]

Wikimedia Commons has media related to Betula nigra.

• Betula nigra Diagnostic photos and information, Morton Arboretum accession 232-51-3.
• Betula nigra images at bioimages.vanderbilt.edu