| Podosemum texanum (Buckley) Bush, 1921 |
| Podosemum trichopodes (Elliott) Bush, 1921 |
| Podosemum virescens Kunth, 1815 |
| Podosemum virginicum (L.) Link, 1827 |
| Poeae R. Br., 1814 |
| Pogochloa S. Moore, 1895 |
| Poidium Nees, 1836 |
| Poinae Dumort., 1829 |
| Pollinia Spreng., 1815 |
| Pollinia brevifolia (Sw.) Spreng., 1815 |
| Pollinia fastigiata (Sw.) Spreng., 1815 |
| Pollinia microstachya (Desv. ex. Ham.) Desv., 1831 |
| Pollinia scoparia (Michx.) Spreng., 1815 |
| Pollinia vaginata Spreng., 1815 |
| Polyantherix Nees, 1838 |
| Polyantherix (Nees) J.G. Sm., 1899 |
| Polyantherix hystrix (Nutt.) Nees, 1838 |
| Polyneura Peter, 1929 |
| Polyodon Kunth, 1815 |
| Polyodon distichus Kunth, 1815 |