| 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 |
| Cassia seleriana Harms, 1899 |
| Cassia septemtrionalis Viv., 1802 |
| Cassia serpens L., 1762 |
| Cassia siamea Lam., 1785 |
| Cassia simulans (Britton & Rose) Lundell, 1937 |
| Cassia skinneri Benth., 1871 |
| Cassia spectabilis DC., 1813 |
| Cassia standleyi (Britton & Rose) Standl., 1937 |
| Cassia stenocarpa Vogel, 1837 |
| Cassia stenosepala L.B. Sm. & B.G. Schub., 1939 |
| Cassia strobilacea Kunth, 1823 |
| Cassia tarantan Kunth, 1823 |
| Cassia tenuicaulis M.E. Jones, 1933 |