Family of Betulaceae
Betula alba birch (berk)
Alnus rubra alder (els)
Coryllus avellana hazel (hazelaar)
Carpinus betulus hornbeam (haagbeuk)
Ostrya virginiana hop-hornbeam, ironwood
Many subvarieties (Species) are know in homeopathy for example:
Betula alba, lenta, papyrifera, pumila and verrucosa
Alnus crispa, glutinosa and rubra
For now it is difficult enough to diffentiate one Genus from the other.
We are not yet able to see a difference between the various Species.