River Birch

''Betula nigra'' 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.
It is a deciduous tree growing to 25 to 30 metres with a trunk 50 to 150 centimetres 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 cm long and 3–6 cm broad, with a serrated margin and five to twelve pairs of veins. 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.