Hornbeam Hornbeam Hornbeams are hardwood trees in the flowering plant genus "Carpinus" in the birch family Betulaceae. The 30–40 species occur across much of the temperate regions of the Northern Hemisphere. The common English name "hornbeam" derives from the hardness of the woods (likened to "horn") and the Old English "beam" "tree" (cognate with German "Baum"). The "American hornbeam" is also occasionally known as "blue-beech", "ironwood", or "musclewood", the first from the resemblance of the bark to that of the American beech "Fagus grandifolia", the other two from the hardness of the wood and the muscular appearance of the trunk, respectively.
Beech bark disease to spread to the south and west. The first case of beech bark disease in the United States was reported in 1929 in Massachusetts. By 2004, the disease had spread as far west as Michigan and as far south as western North Carolina. For beech bark disease to occur, two components are required, an insect and a fungus. The beech scale insect, "Cryptococcus fagisuga", is invasive to North America and is host-specific, feeding exclusively on beech trees. It can be observed on the trunk and limbs of the tree as woolly, white tufts that will later develop into broad strips.