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.
Alnus cordata with a very long season in leaf, from April to December in the Northern Hemisphere; they are alternate, cordate (heart-shaped), rich glossy green, 5–12 cm long, with a finely serrated margin. The slender cylindrical male catkins are pendulous, reddish and up to 10 cm long; pollination is in early spring, before the leaves emerge. The female catkins are ovoid, when mature in autumn 2–3 cm long and 1.5–2 cm broad, dark green to brown, hard, woody, and superficially similar to some conifer cones. The small winged seeds disperse through the winter, leaving the old woody, blackish 'cones' on the tree