| Ageratina leiocarpa (B.L. Rob.) Gage ex B.L. Turner, 1997 |
| Ageratina lemmonii (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina leptodictyon (A. Gray) R.M. King & H. Rob., 1970 |
| Ageratina liebmannii (Sch. Bip. ex Klatt) R.M. King & H. Rob., 1970 |
| Ageratina ligustrina (DC.) R.M. King & H. Rob., 1970 |
| Ageratina loeseneri (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina lucida (Ortega) R.M. King & H. Rob., 1970 |
| Ageratina macdonaldii B.L. Turner, 1990 |
| Ageratina macvaughii R.M. King & H. Rob., 1978 |
| Ageratina mairetiana (DC.) R.M. King & H. Rob., 1970 |
| Ageratina mairetiana var. elucens (McVaugh) B.L. Turner, 1987 |
| Ageratina mairetiana var. mairetiana (DC.) R.M. King & H. Rob., 1970 |
| Ageratina malacolepis (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina manantlana B.L. Turner, 1988 |
| Ageratina mariarum (B.L. Rob.) R.M. King & H. Rob., 1970 |
| Ageratina markporteri B.L. Turner, 2012 |
| Ageratina mayajana B.L. Turner, 2006 |
| Ageratina mazatecana B.L. Turner, 2006 |
| Ageratina megacephala B.L. Turner, 2010 |
| Ageratina megaphylla B.L. Turner, 2013 |