| Palafoxia riograndensis Cory, 1946 |
| Palafoxia rosea (Bush) Cory, 1946 |
| Palafoxia rosea var. ambigua Shinners, 1952 |
| Palafoxia rosea var. rosea (Bush) Cory, 1946 |
| Palafoxia sphacelata (Nutt. ex Torr.) Cory, 1946 |
| Palafoxia texana DC., 1836 |
| Palafoxia texana var. ambigua (Shinners) B.L. Turner & M. Morris, 1976 |
| Palafoxia texana var. robusta (Rydb.) B.L. Turner & M. Morris, 1976 |
| Palafoxia texana var. texana DC., 1836 |
| Paleista Raf., 1837 |
| Pallasia L'Hér. ex Aiton, 1789 |
| Paneroa E.E. Schill., 2008 |
| Paneroa stachyofolia (B.L. Rob.) E.E. Schill., 2008 |
| Parthenice A. Gray, 1853 |
| Parthenice mollis A. Gray, 1853 |
| Parthenice mollis var. mollis A. Gray, 1853 |
| Parthenice mollis var. peninsularis Sauck, 1975 |
| Parthenium L., 1753 |
| Parthenium arctium Bartlett, 1909 |
| Parthenium argentatum A. Gray, 1859 |