Both Hophornbeam (Ostrya virginiana) and American Hornbeam (Carpinus caroliniana) belong to the birch family (Betulaceae), but they are distinct species. The trunk bark is one defining feature...the bark on middle-age Carpinus trees is "muscular" and fairly smooth, having vertical ridges, whereas Ostrya bark isn't ridged and becomes exfoliating (flakes off) with age. The other main distinguishing feature is the seeds, which are produced in loose hanging clusters with prominent "wings" for Carpinus, and hops-like (or vaguely pine cone-like), smaller, denser, paler-colored clusters for Ostrya. You can visit the image galleries for each species using the linked page above. (Click on the species name instead of the genus name to go directly to the species page.)

Tree ID keys, like one from Virginia Tech dendrology, can be useful in using other features to distinguish one species from another. (For example, dormant bud and leaf scar characteristics.) That tree database does include entries for both American Hornbeam (plus European and Japanese Hornbeams) and Hophornbeam.

Miri

Both Ostrya and Carpinus share the common name Ironwood, as do a couple of other non-native tree species as well.

Miri

Thanks Miri

You're welcome.