| Ageratina amblyolepis (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina anchistea (Grashoff & Beaman) R.M. King & H. Rob., 1972 |
| Ageratina areolaris (DC.) Gage ex B.L. Turner, 1997 |
| Ageratina arsenei (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina aschenborniana (Schauer) R.M. King & H. Rob., 1970 |
| Ageratina astillera (B.L. Turner) B.L. Turner, 1987 |
| Ageratina atrocordata (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina ayerscottiana B.L. Turner, 1995 |
| Ageratina barriei B.L. Turner, 1987 |
| Ageratina beamanii B.L. Turner, 1987 |
| Ageratina bellidifolia (Benth.) R.M. King & H. Rob., 1970 |
| Ageratina betulifolia (Greene) R.M. King & H. Rob., 1970 |
| Ageratina blepharilepis (Sch. Bip.) R.M. King & H. Rob., 1970 |
| Ageratina bobjansenii B.L. Turner, 1996 |
| Ageratina brandegeana (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina breedlovei R.M. King & H. Rob., 1985 |
| Ageratina brevipes (DC.) R.M. King & H. Rob., 1970 |
| Ageratina bustamenta (DC.) R.M. King & H. Rob., 1970 |
| Ageratina caeciliae (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina calaminthifolia (Kunth) R.M. King & H. Rob., 1970 |