Subject
- Specific Epithet: rothii 9
- Specific Epithet: rugelii 4
- Specific Epithet: rugifolia 4
- Specific Epithet: rugosum 7
- Specific Epithet: rupestris 1
- Specific Epithet: ruralis 4
- Specific Epithet: russowii 8
- Specific Epithet: rutabulum 4
- Specific Epithet: salebrosum 13
- Specific Epithet: sarmentosum 5
- Specific Epithet: schreberi 8
- Specific Epithet: schreberiana 1
- Specific Epithet: scitum 7
- Specific Epithet: scoparium 17
- Specific Epithet: scorpioides 2
- Specific Epithet: scutatus 1
- Specific Epithet: seductrix 21
- Specific Epithet: selwynii 7
- Specific Epithet: serpens 11
- Specific Epithet: serrulatum 26