| Carex schiedeana var. perstricta (Mack.) F.J. Herm., 1974 |
| Carex schiedeana var. schiedeana Kunze, 1842 |
| Carex schiedeana var. stellata (Mack.) F.J. Herm., 1974 |
| Carex schottii Dewey, 1859 |
| Carex seatoniana L.H. Bailey, 1898 |
| Carex senta Boott, 1867 |
| Carex spilocarpa Steud., 1855 |
| Carex spissa L.H. Bailey, 1886 |
| Carex spissa var. seatoniana (L.H. Bailey) Kük., 1909 |
| Carex spissa var. spissa L.H. Bailey, 1886 |
| Carex spissa var. ultra (L.H. Bailey) Kük., 1909 |
| Carex standleyana Steyerm., 1952 |
| Carex stellata Mack., 1935 |
| Carex steyermarkii Standl., 1947 |
| Carex straminea Willd. ex Schkuhr, 1801 |
| Carex straminea var. australis L.H. Bailey, 1889 |
| Carex subfusca W. Boott, 1880 |
| Carex subulata J.F. Gmel., 1791 |
| Carex tehuacana Reznicek & S. González, 2021 |
| Carex tenejapensis Reznicek & S. González, 1999 |