| Cassia pilosa L., 1762 |
| Cassia pilosior (J.F. Macbr.) H.S. Irwin & Barneby, 1965 |
| Cassia polyantha Collad., 1816 |
| Cassia polyphylla Jacq., 1791 |
| Cassia praetexta Vogel, 1837 |
| Cassia pringlei Rose, 1899 |
| Cassia pubigera Lag., 1816 |
| Cassia pumilio A. Gray, 1850 |
| Cassia punctulata Hook. & Arn., 1840 |
| Cassia purpusii Brandegee, 1906 |
| Cassia quiedondilla Micheli, 1903 |
| Cassia quinquangulata Rich., 1792 |
| Cassia racemosa Mill., 1768 |
| Cassia reticulata Willd., 1809 |
| Cassia riparia Kunth, 1824 |
| Cassia riparia var. pilosa Benth., 1870 |
| Cassia ripleyana H.S. Irwin & Barneby, 1975 |
| Cassia roemeriana Scheele, 1848 |
| Cassia rotundifolia Pers., 1805 |
| Cassia rufa M. Martens & Galeotti, 1843 |