| Parthenium parviceps S.F. Blake, 1924 |
| Parthenium rollinsianum Rzed., 1959 |
| Parthenium schottii Greenm. ex Millsp. & Chase, 1904 |
| Parthenium stramonium Greene, 1901 |
| Parthenium tomentosum DC., 1836 |
| Parthenium tomentosum var. stramonium (Greene) Rollins, 1950 |
| Parthenium tomentosum var. tomentosum DC., 1836 |
| Pectidinae Less., 1832 |
| Pectidium Less., 1831 |
| Pectidium punctatum Less., 1831 |
| Pectidopsis DC., 1836 |
| Pectis L., 1759 |
| Pectis ambigua Fernald, 1897 |
| Pectis amplifolia D.J. Keil, 1989 |
| Pectis angustifolia Torr., 1827 |
| Pectis angustifolia var. angustifolia Torr., 1827 |
| Pectis angustifolia var. fastigiata (A. Gray) D.J. Keil, 1977 |
| Pectis angustifolia var. subaristata A. Gray, 1852 |
| Pectis angustifolia var. tenella (DC.) D.J. Keil, 1977 |
| Pectis aquatica S. Watson, 1888 |