The river birch (Betula nigra) is a deciduous member of the Birch family, and is the lone native American birch that grows in lowlands in the Southeast. River birch is a tree of stream and riverbanks, the driest parts of a swamp and fertile bottomlands. River birch has some distinctive features that can help you differentiate it from other birch species you may encounter.
The river birch only grows in the wild in the eastern section of the United States. Its northernmost range is Southern New England; from there, it grows southwards to the northern parts of Florida. From Florida, the river birch's range goes west to eastern Texas and then north through eastern Oklahoma, most of Missouri, eastern Iowa and extreme southern Minnesota. River birch trees exist eastward from that point, with the border of its range dipping into southern portions of Illinois, Indiana and Ohio.
In many instances, the trunk of the river birch splits into multiple stems not far from the base of the tree. This gives the tree a very irregular shape. The river birch is a mid-sized tree. Some are able to grow as tall as 90 feet, but most average between 50 and 70 feet tall. The trunk, if it remains intact and fails to branch into different sections, can be as wide as 3 feet. Often, a river birch will grow leaning out over a stream or river, with its roots entrenched firmly in the bank.
A key point of identification of the river birch is the exfoliating bark on the young trees. The bark peels back in large sections and rolls up to reveal different colors like pink, tan and cream. The older river birch trees develop a thicker scaly bark that is brown-gray in color. The bark on the older specimens will not peel back nearly as much as that on younger trees.
The leaves of the river birch are a vibrant shade of green and will change to yellow in the autumn. Once the leaves change, the University of Connecticut Plant Database website states they will not stay on the branches very long. River birch leaves are oval, as long as 3 inches and as wide as 2 inches. The leaves have doubly toothed edges and taper to a point. When you feel them, you will notice that the stems of the leaves are somewhat hairy.
All birch trees have flowers known as catkins, with female catkins and male catkins existing on the same tree. The male catkins on a river birch are longer than the female version, about 2 to 3 inches long when blooming. The male catkins exist in clusters of twos and threes and are a red-yellow hue, growing at the very ends of the twigs. The female catkins are as long as 1 1/4 inches, and have a covering of minute hairs. Once the wind pollinates them, the female catkins take on the appearance of a very small cone.