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.
Pterocarya fraxinifolia appear in April, the male catkins thick and green, 7.5 – 12.5 cm long, the females longer with less dense flowers, bearing red styles forming fruiting catkins 30 – 50 cm long, the green, winged, nuts approximately 1.8 cm wide. The species is fast growing and grows best on flat ground or shallow slopes near river banks and in deep moist soils. The climate associated with the distribution of this tree includes mild winters and mild humid summers. It generally grows in mixed stands with other species and rarely grows in pure stands. Fossils of "Pterocarya fraxinifolia" have been described