| Ageratina prunellifolia (Kunth) R.M. King & H. Rob., 1970 |
| Ageratina purpusii (Brandegee) R.M. King & H. Rob., 1970 |
| Ageratina queretaroana B.L. Turner, 1987 |
| Ageratina rafaelensis (J.M. Coult.) R.M. King & H. Rob., 1970 |
| Ageratina ramireziorum (Espinosa) B.L. Turner, 1987 |
| Ageratina ramonensis (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina repens (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina reserva B.L. Turner, 2012 |
| Ageratina resinifera H. Rob., 2001 |
| Ageratina rhodopoda (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina rhomboidea (Kunth) R.M. King & H. Rob., 1970 |
| Ageratina riparia (Regel) R.M. King & H. Rob., 1970 |
| Ageratina riskindii B.L. Turner, 1987 |
| Ageratina rivalis (Greenm.) R.M. King & H. Rob., 1970 |
| Ageratina robinsoniana (Greene) B.L. Turner, 1987 |
| Ageratina rollinsii B.L. Turner, 1983 |
| Ageratina rothrockii (A. Gray) R.M. King & H. Rob., 1970 |
| Ageratina rubricaulis (Kunth) R.M. King & H. Rob., 1970 |
| Ageratina rufa (Greene) R.M. King & H. Rob., 1970 |
| Ageratina rupicola (B.L. Rob. & Greenm.) R.M. King & H. Rob., 1970 |