Subject
- Specific Epithet: neo-mexicana 3
- Specific Epithet: neomexicana 1
- Specific Epithet: nervosa 5
- Specific Epithet: nigritum 4
- Specific Epithet: nitens 3
- Specific Epithet: norvegicum 13
- Specific Epithet: novae-angliae 25
- Specific Epithet: nutans 13
- Specific Epithet: obconica 4
- Specific Epithet: obscura 1
- Specific Epithet: obtusifolium 1
- Specific Epithet: obtusifolius 5
- Specific Epithet: ochraceum 8
- Specific Epithet: oederiana 1
- Specific Epithet: ohioense 76
- Specific Epithet: ontariense 11
- Specific Epithet: orbicularis 1
- Specific Epithet: orientale 1
- Specific Epithet: osmundoides 21
- Specific Epithet: oxycladon 23