| Planodes Greene, 1912 |
| Planodes mexicanum (S. Watson) Rollins, 1941 |
| Planodes virginicum (L.) Greene, 1912 |
| Pleiocardia Greene, 1904 |
| Pleurophragma Rydb., 1907 |
| Poliophyton O.E. Schulz, 1933 |
| Poliophyton pubens (A. Gray) O.E. Schulz, 1933 |
| Porphyrocodon Hook. f., 1862 |
| Pritzelago Kuntze, 1891 |
| Pseudobraya Korsh., 1896 |
| Psychineae DC., 1821 |
| Pteroneurum DC., 1821 |
| Pterygiosperma O.E. Schulz, 1924 |
| Quidproquo Greuter & Burdet, 1983 |
| Radicula Moench, 1794 |
| Radicula dictyota Greene, 1905 |
| Radicula mexicana (Moc., Sessé & Cerv. ex DC.) Standl., 1925 |
| Radicula pacifica (Howell) Greene, 1905 |
| Radicula sinuata (Nutt.) Greene, 1905 |
| Radicula tenerrima (Greene) Greene, 1905 |