There are two trees common in our woods that don’t get much attention. They are typically small trees that stay underneath the main canopy and make do with what sunlight they can get. They have no timber value, but do create a more diversified forest and food and shelter for wildlife.
Ironwood (Carpinus caroliniana), also called American hornbeam, blue beech or muscle tree, is usually found on moist soil near streams and drains. It has a smooth, gray bark with a fluted trunk, looking like the bulging arm muscles of a weight lifter. These unusual stems are striking enough to make this tree worthy as a landscape plant. The twigs grow in a zigzag pattern, and the leaves are spear shaped with a sawtooth edge. These edge teeth come in two sizes, which is described by science folk as “double toothed.” The wood is where the name ironwood is derived, as it is very hard and heavy. The name “hornbeam” comes from the use of “horn” for toughness, and “beam “as an old word for tree. Ironwood has no commercial value, but several bird species and squirrels eat the nutlet seeds, and the buds are food for upland gamebirds.
Hop-hornbeam (Ostrya virginiana) is not related to Ironwood, but also has a very heavy, dense wood that is 30 percent stronger than oak. It can be found on dryer slopes and has a brown, flaky bark with tiny scales that twist out a little. The leaves are similar to ironwood, but turn yellow in the fall instead of red. This is not a showy tree and easily overlooked. The “hop” part of the name is from the hop-like scales around the nut that look as though the nut-like fruit is enclosed in a small paper bag. Hop-hornbeam rarely gets large enough to be of commercial use, but pioneers did use the tough wood for tool handles, wagon spokes and axles, and an excellent pry bar. The nutlet seeds are used by quail and other birds, as are the buds. Deer do occasionally browse the twigs in winter.
While trees like ironwood and hop-hornbeam don’t sound important, they occupy a level in the forest called the mid-story or under-story, an level below the taller trees with their heads in the sun (the over-story), and above the shrub layer. This “middle ground” forms a habitat very important to many species of songbirds, so these trees do have their place in the woods. This “layered” structure of the forest is very efficient in utilizing all available sunlight and providing species diversity of both plants and animals.
Steve Roark is the area forester in Tazewell, Tennessee, for the Tennessee Department of Agriculture, Forestry Division.