River birch, Betula nigra, is a native American tree found in the eastern U.S. from southern Minnesota to northern Florida. In Ohio its natural habitat is limited to the southeast portion of the state, an area of acid soil. However this tree has adapted well to urban cultures and is often grown because of its interesting bark. One cultivar, “Heritage” was named the “Urban Tree of the Year for 2002” by the Society of Municipal Arborists. Besides the interesting bark, this cultivar is known for rapid growth, strong wood, and resistance to the bronze birch borer.
The river birch’s natural habitat is moist lowlands and swampy areas where it helps stops the erosion of streambanks. The seed which it produces in May and June floats downstream to a suitable location where it germinates the same season. The seedlings and young trees flourish along the river bank and help shore up the soil.
At maturity, the river birch is a medium sized tree which reaches about 70 feet with a 50 foot spread. It has simple alternate leaves about two to three inches long with a coarsely toothed edge. The upper surface of the leaves is a dark green, the lower a pale, yellowgreen. In fall the leaves turn a dull yellow. On younger trees, the bark has the paper curls which make it attractive for landscaping; on older trees, the reddish brown bark becomes thick and deeply furrowed.
Male and female flowers grow on the same tree. The males are borne on slender drooping catkins about 3 inches long and the females on 1-inch long, erect, conelike catkins that turn brown and bear a large number of little winged nutlets. The seeds provide food for birds and mammals; deer will browse on the twigs and buds. The wood is not largely harvested but has been used for woodenware, in turnery, and for pulpware.
Site selection is important as the river birch needs a sandy, acidic soil with a pH of 6.5 or less. The site should be also moist, in full sun, and large enough for a wide spreading root system. River birch is resistant to the bronze birch borer and requires little maintenance except for watering during drought conditions. It can be pruned to keep branches above sidewalks and driveways, but pruning should be done in the winter when the tree is dormant.
This winter my river birch has been spectacular. It sits near a bird feeder and the birds like to perch in its branches. The snow sets off the color of the curling bark against the lighter trunk. It is a pleasure to look at. For winter interest in the landscape, it is definitely a tree worth keeping.