Subject
- Specific Epithet: agassizii 2
- Specific Epithet: agraria 1
- Specific Epithet: albidum 11
- Specific Epithet: alleghaniense 23
- Specific Epithet: alpestre 3
- Specific Epithet: alpestris 1
- Specific Epithet: alpicola 14
- Specific Epithet: alpinum 2
- Specific Epithet: alternifolium 31
- Specific Epithet: americanum 13
- Specific Epithet: amphibola 1
- Specific Epithet: ampullaceum 1
- Specific Epithet: angustatum 12
- Specific Epithet: angustatus 1
- Specific Epithet: angustirete 1
- Specific Epithet: annotina 3
- Specific Epithet: annulatum 1
- Specific Epithet: anomala 1
- Specific Epithet: anomalum 2
- Specific Epithet: aphylla 1