The river birch is a fast-growing, water-loving, deciduous tree, native to much of the United States. Its scientific name is Betula nigra. Unlike other birches that have white barks, the river birch's bark is reddish brown and curls and peels naturally, adding visual interest to the plant. River birch is also more pest-resistant than other birches, making it a popular and relatively care-free choice for landscaping.
River birch are tall, graceful-looking trees. They have cinnamon-colored bark that peels from the trunk. The leaves are oval, around 1-1/2 to 3 inches long, and 1 to 2 inches wide with slightly serrated margins and are shiny and medium green in color. The tiny flowers are green or brown and are unimpressive and inconspicuous. The fruit forms as 3-inch long clusters of seeds called catkins.
This is a fast-growing and hardy tree, often putting on more than 2 feet of growth per year. They are at their best in hardiness zones 4 through 7, but will grow to zone 9, based on the United States Agricultural Department Hardiness Zone map. The plant is relatively short-lived, lasting only 30 to 40 years in urban environments. The tree thrives in moist conditions, hence the name river birch. The branches of the tree tend to droop. River birches often produce multiple leader trunks from the same plant.
River birch grow to between 40 and 70 feet tall, and typically spread to 40 to 60 feet wide. Though river birch grows quite tall, the trunk of the tree usually remains relatively thin. The canopy of the tree is somewhat oval shaped and fairly dense.
River birches grow well in full sun, however, they may tolerate partial shade. While they can handle some drought conditions, river birches prefer wetter soils and will grow better if irrigated regularly. The soil should not be too alkaline and can range from sandy loam to clay. Because of the vertical nature of this tree, it can be planted closer to houses than other trees. Young trees will require pruning of the lower branches to prevent them from drooping to the ground.
The river birch is a popular landscape tree and is often used as a centerpiece in the yard. Its distinctive bark and graceful appearance make it a desirable addition to the landscape. Because it is the most resistant of the birches to boring insects, particularly the bronze birch borer, it is often chosen over other birch species. As it appreciates wet conditions, it can also be used to control erosion along riverbanks.