| Cassia parralensis H.S. Irwin & Barneby, 1975 |
| Cassia patellaria DC. ex Collad., 1816 |
| Cassia patellaria var. glabrata Vogel, 1837 |
| Cassia patellaria var. ramosa Vogel, 1837 |
| Cassia pavoniana G. Don, 1832 |
| Cassia pendula Humb. & Bonpl. ex Willd., 1809 |
| Cassia pentagonia Mill., 1768 |
| Cassia peralteana Kunth, 1824 |
| Cassia petensis (Britton & Rose) Standl., 1935 |
| Cassia picachensis Brandegee, 1915 |
| Cassia pilifera Benth., 1871 |
| Cassia pilifera var. subglabra S. Moore, 1895 |
| Cassia pilosa L., 1762 |
| Cassia pilosior (J.F. Macbr.) H.S. Irwin & Barneby, 1965 |
| Cassia polyantha Collad., 1816 |
| Cassia praetexta Vogel, 1837 |
| Cassia pringlei Rose, 1899 |
| Cassia pubigera Lag., 1816 |
| Cassia pumilio A. Gray, 1850 |
| Cassia punctulata Hook. & Arn., 1840 |