The river birch has quite a distinct identity, separate from the rest of its family. Unlike its other two common cousins, the European weeping birch and the paper birch, the bark of a river birch is usually dark gray-brown to pinkish-brown. This name is given to any tree of the genus Betula, and is botanically known as Betula nigra. It is native to North America.
This tree can achieve a height of about 50 to 90 feet under favorable climatic conditions. It grows along the lines of a central leader that eventually gets divided into several low lateral upright branches. As a young tree, it has a narrow, oval to pyramidal crown that spreads wider (about 40 - 60 inches) and becomes more denser as it gets older. However, it still gives a neat pyramidal look. One of the interesting facts about it is its bark. Unlike its cousins, it is smooth when young, and more brown and scaly when it begins to mature. It does not have the white-silver colored bark usually associated with other birch trees. In fact, its bark has a curly peeling appearance.
Its leaves are simple, alternately arranged, shaped ovate or rhomboid with margins that are double and serrated. Each leaf is about two to four inches in length. The leaves are green in color that turn yellow in fall; however, this tree is not planted for its fall foliage. In mid-spring, it bears pendulous male catkins and erect female catkins. The flowers are brown and have no ornamental value. They are wind-pollinated. Its brown fruit is elongated and dry, shaped like a cone, and it is about one to three inches in size. Upon ripening, the hard cover of the cone cracks open to release plenty of tiny, three-winged seeds.
It is not very popular as a garden tree, but its strength, adaptability to wind, and erosion control properties make it a popular one in terms of a river bank landscape tree. It is planted along river banks and streams, where it is able to tolerate moderate flooding and is excellent for holding banks during a heavy flow and prevents soil erosion. As long as it is provided with moist conditions, it tolerates oxygen depleted soil and clay soil. Although it can tolerate a mild drought, it cannot bear excess heat. It needs plenty of water. New cultivars like 'Heritage' have been introduced to withstand drought conditions. Further, due to its adaptability to different soils it is used for strip mine reclamation and soil erosion control.
This is a tree with less litter mess and hardly any pest problems. It stands upright with its strong branches. So, it is popularly used in large estates, golf courses, public parks, and grounds to arrest the flow of wind. It is surprisingly resistant to the bronze birch borer which infects its cousins. Its leaves are a food source for the white-tailed deer and the seeds for the wild turkey and grouse. Birds such as redpolls and pine siskins use the flowers. Further, it has industrial as well as domestic uses. The sap is used to make a sweetener and fermented to make birch beer or vinegar. The wood is used by cottage industries to make wooden articles, like shoes, furniture, toys, and baskets. The bark is said to have medicinal uses as well.
With new cultivars on offer, some river birch trees now have a slightly whitish bark. Combined with their no fuss for growth or maintenance, they can be surely be your ornamental trees!