Oceaniopteris, Genus
Odontosoria, Genus
Oenotrichia, Genus
Oleandra, Genus
Olfersia, Genus
Onoclea, Genus
Onocleopsis, Genus
Onychium, Genus
Ophioderma, Genus
Ophioglossum, Genus
Oreogrammitis, Genus
Oreopteris, Genus
Ormopteris, Genus
Osmolindsaea, Genus
Osmunda, Genus
Osmundastrum, Genus