| Senecio rosei Greenm., 1907 |
| Senecio roseus Sch. Bip., 1845 |
| Senecio rotundifolius Sessé & Moc., 1890 |
| Senecio runcinatus Less., 1831 |
| Senecio rzedowskii García-Pérez, 1985 |
| Senecio salignus DC., 1837 |
| Senecio sandersianus B.L. Turner, 2002 |
| Senecio sandersii B.L. Turner, 1996 |
| Senecio sanguisorbae DC., 1838 |
| Senecio santarosae Greenm., 1907 |
| Senecio scalaris Greene, 1900 |
| Senecio scalaris var. carmenensis C.C. Freeman, 1989 |
| Senecio scalaris var. parrasianus (Greenm.) C.C. Freeman, 1989 |
| Senecio schaffneri Sch. Bip. ex Klatt, 1888 |
| Senecio schumannianus Schauer, 1847 |
| Senecio sclerophyllus Hemsl., 1881 |
| Senecio seemannii Sch. Bip. ex Seem., 1856 |
| Senecio semperamatae T.M. Barkley, 1978 |
| Senecio sennikovii Kottaim., 2021 |
| Senecio serra Hook., 1834 |