| Ageratina mygindifolia (A. Gray) R.M. King & H. Rob., 1970 |
| Ageratina nelsonii R.M. King & H. Rob., 1972 |
| Ageratina neohintoniorum B.L. Turner, 1987 |
| Ageratina nesomii B.L. Turner, 1983 |
| Ageratina oaxacana (Klatt) R.M. King & H. Rob., 1975 |
| Ageratina oligocephala (DC.) R.M. King & H. Rob., 1970 |
| Ageratina oppositifolia (A. Gray) B.L. Turner, 1987 |
| Ageratina oreithales (Greenm.) B.L. Turner, 1987 |
| Ageratina ovilla (Standl. & Steyerm.) R.M. King & H. Rob., 1970 |
| Ageratina ozolotepecana B.L. Turner, 2010 |
| Ageratina pachypoda (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina pacifica (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina palmeri (A. Gray) Gage ex B.L. Turner, 1997 |
| Ageratina parayana (Espinosa) B.L. Turner, 1987 |
| Ageratina pauciflora B.L. Turner, 2013 |
| Ageratina paupercula (A. Gray) R.M. King & H. Rob., 1970 |
| Ageratina pazcuarensis (Kunth) R.M. King & H. Rob., 1970 |
| Ageratina pelotropha (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina pendula Panero & Villaseñor, 1997 |
| Ageratina peracuminata R.M. King & H. Rob., 1978 |