| Cyperus sellowianus (Kunth) T. Koyama, 1960 |
| Cyperus semiochraceus Boeckeler, 1878 |
| Cyperus semitribrachiatus Boeckeler, 1870 |
| Cyperus sertularinus Liebm., 1850 |
| Cyperus sertularinus var. discigerus (Liebm.) Kük., 1936 |
| Cyperus seslerioides Kunth, 1815 |
| Cyperus seslerioides f. minor C.B. Clarke, 1893 |
| Cyperus seslerioides var. minor (C.B. Clarke) Kük., 1936 |
| Cyperus sesquiflorus (Torr.) Mattf. & Kük., 1936 |
| Cyperus sesquiflorus subsp. sesquiflorus (Torr.) Mattf. & Kük., 1936 |
| Cyperus simplex Kunth, 1815 |
| Cyperus sordidus J. Presl & C. Presl, 1830 |
| Cyperus speciosus Vahl, 1806 |
| Cyperus spectabilis Link, 1827 |
| Cyperus spectabilis var. coarctatus Boeckeler, 1868 |
| Cyperus spectabilis var. parryi (Britton ex C.B. Clarke) Kük., 1936 |
| Cyperus spectabilis var. scaberrimus (Nees) Boeckeler, 1868 |
| Cyperus sphacelatus Rottb., 1772 |
| Cyperus sphaerolepis Boeckeler, 1868 |
| Cyperus sphaerostachys Link, 1820 |