Subject
- Specific Epithet: pagorum 2
- Specific Epithet: pallescens 19
- Specific Epithet: pallidisetum 11
- Specific Epithet: pallidum 21
- Specific Epithet: paludicola 1
- Specific Epithet: paludosum 3
- Specific Epithet: palustre 15
- Specific Epithet: papillosa 4
- Specific Epithet: papillosum 6
- Specific Epithet: parasiticus 2
- Specific Epithet: parvulus 5
- Specific Epithet: pellucida 11
- Specific Epithet: pellucidum 5
- Specific Epithet: pennata 4
- Specific Epithet: pennsylvanica 7
- Specific Epithet: pensilvanicum 10
- Specific Epithet: perichaetiale 2
- Specific Epithet: pilifer 2
- Specific Epithet: pilifera 6
- Specific Epithet: piliferum 7