The winter twigs are slender, red-brown in color, and covered with white conspicuous lenticels or pores. The twigs have a characteristic aromatic birch odor and taste. The bark of river birch changes with age of the tree. When young, the bark flakes into thin, papery pieces that are first orange and white and later orange brown in color. The bark of mature trees is scaly and dark red-brown to black in color and often resembles the bark of cherry.
River birch is the most widely distributed birch in Iowa.
It is typically found along stream bottoms in eastern and central Iowa, but is also found scattered in south central and southwestern Iowa. River birch tolerates a wide variety of sites. It prefers moist soils, but will grow on sites from wet to very dry. It may suffer from iron chlorosis on basic soils. On some sites, especially wet sites, it is often found growing in pure stands.