Most people study leaves when they are trying to identify a tree. However, leaves are only one identifying characteristic and often not the best one. Trees can also be identified by their fruit, seeds, overall shape, fall coloration, habitat, buds and bark.
Several of my favorite winter trees are birches. Their distinctive bark makes them easy to identify, even in January. Five species of birch are native to Pennsylvania, including black (also called sweet), paper, river, yellow and gray birch. Although birch trees have shed their leaves long ago, yellow birch (Betula alleghaniensis) still stands out as a unique tree in the winter forest.
If you are at least a little familiar with trees, the mention of “birch” likely brings an image of white bark accented with horizontal black lines. While this is a great “birch” connection, two native birch species share similar white bark, as do several introduced species. The bark of yellow birch is unique.
Yellow birch’s shiny, straw-yellow or bronze-colored bark peels horizontally into paper-thin curls and makes this tree easy to identify during any season. The twigs of yellow birch are also shiny and have a faint wintergreen smell when snapped.
Yellow birch is a medium-sized tree with a well-developed root system. It can grow to a height of 60 to 80 feet. It has oval, simple, alternate leaves with pinnate (feather-like) venation. Like other birches, its deciduous leaves turn bright yellow in the fall.
Both yellow and black birch (Betula lenta) have similar leaves and their twigs both smell like wintergreen. However, their barks and buds are not alike. Black birch has smooth buds and the buds of yellow birch are hairy.
Yellow birch grows along mountain streams. It prefers cooler northern slopes or damp bottomlands. It is frequently found in association with beech, hemlock, and black birch. It often grows near sugar maple even though sugar maple roots produce a chemical that retards the growth of yellow birch seedlings.
Yellow birch is found from Maine to Minnesota and south along the mountains into North Carolina and Tennessee. It grows throughout much of Pennsylvania.
This birch fits into the forest ecology web in many ways. The buds are a favorite winter food of the ruffed grouse. Many species of birds eat their seeds. Rabbits, beaver and deer eat the bark and twigs. Numerous species of insects, including the larva of the large cecropia moth and the mourning cloak butterfly also feed on its leaves. Earthworms recycle the fallen leaves into soil nutrients.
Yellow birch is the most valuable hardwood tree in southern Canada. According to the American Hardwood Association, its wood is used for furniture, paneling, doors, cabinets, flooring, toothpicks and wooden toys. About 75 percent of the wood marketed as “birch” comes from this tree.
Yellow birch sapwood is white, and the heartwood is a reddish-brown color. Both woods have a straight, fine grain that is often confused with maple. The wood is heavy, reasonably hard and strong. It takes steaming and bending well.
Its two-toned wood gives birch floors a beautiful rustic appearance. Over the years, yellow birch has been one of the main woods used to distill wood alcohol, tar and oils of wintergreen. It continues to be used to make paper and charcoal.
Every outdoors person should know that, even when wet, the paper-thin bark curls stripped from a yellow birch tree are an excellent fire starter. They burn like paper soaked in gasoline.
Native Americans burned the bark to keep away mosquitoes, and they chewed the inner bark to relieve stomach cramps. A chemical extracted from yellow birch bark is still used to treat inflammation.
If you have ever encountered a tree whose roots appeared to start a foot or more above the ground, you were likely looking at a yellow birch. The winged seeds of yellow birch germinate best on top of a rotting log or stump. The birch tree continues to grow, but the log or stump eventually rots away – leaving a woodland oddity.