| Senecio flaccidus var. flaccidus Less., 1830 |
| Senecio flaccidus var. monoensis (Greene) B.L. Turner & T.M. Barkley, 1990 |
| Senecio floresiorum B.L. Turner, 1993 |
| Senecio galeottii Hemsl., 1881 |
| Senecio galicianus McVaugh, 1972 |
| Senecio galicianus var. manantlanensis R.R. Kowal, 1991 |
| Senecio gentryi (H. Rob. & Brettell) B.L. Turner & T.M. Barkley, 1989 |
| Senecio gerberifolius Sch. Bip. ex Hemsl., 1881 |
| Senecio gesneriifolius B.L. Turner, 1987 |
| Senecio ghiesbreghtii Regel, 1860 |
| Senecio ghiesbreghtii var. pauciflorus J.M. Coult., 1891 |
| Senecio ghiesbreghtii var. uspantanensis J.M. Coult., 1895 |
| Senecio gilgii Greenm., 1907 |
| Senecio glinophyllus (H. Rob. & Brettell) McVaugh, 1984 |
| Senecio godmanii Hemsl., 1881 |
| Senecio goldmanii Greene, 1911 |
| Senecio gonzaleziae B.L. Turner, 1985 |
| Senecio gracilipes B.L. Rob. & Greenm., 1895 |
| Senecio grahamii Benth., 1839 |
| Senecio grandifolius Less., 1830 |