| Psilantha (K. Koch) Tzvelev, 1968 |
| Psilochloa Launert, 1970 |
| Psilopogon Hochst. ex A. Rich., 1852 |
| Pterium Desv., 1813 |
| Pterochloris (A. Camus) A. Camus, 1957 |
| Pteropodium Steud., 1841 |
| Puccinellia Parl., 1848 |
| Puccinellia carinata (Griseb.) Ponert, 1974 |
| Puccinellia fendleriana (Steud.) Ponert, 1974 |
| Quinquesetum Parodi, 1946 |
| Rabdochloa P. Beauv., 1812 |
| Rabdochloa domingensis (Jacq.) P. Beauv., 1812 |
| Rabdochloa dubia (Kunth) Kuntze ex Stuck., 1904 |
| Rabdochloa imbricata (Thurb.) Kuntze, 1891 |
| Rabdochloa mucronata (Michx.) P. Beauv., 1812 |
| Rabdochloa spicata (Nees) Kuntze ex Stuck., 1904 |
| Rabdochloa virgata (Sw.) P. Beauv., 1812 |
| Raddia Mazziari, 1834 |
| Raram Adans., 1763 |
| Raspailia J. Presl, 1830 |