| Carex cabralii Reznicek & S. González, 2021 |
| Carex caeligena Reznicek, 1990 |
| Carex camporum Mack., 1910 |
| Carex capitata L., 1759 |
| Carex caxinensis F.J. Herm., 1971 |
| Carex celsa (L.H. Bailey) Piper, 1915 |
| Carex chiapensis F.J. Herm., 1967 |
| Carex chihuahuensis Mack., 1908 |
| Carex chlorocarpos Liebm., 1850 |
| Carex chordalis Liebm., 1850 |
| Carex ciliaris Fernald, 1907 |
| Carex cladostachya Wahlenb., 1803 |
| Carex cochranei Reznicek, 1993 |
| Carex comosa Boott, 1846 |
| Carex complanata Torr. & Hook., 1836 |
| Carex complanata subsp. tropicalis Reznicek & S. González, 2001 |
| Carex complexa Reznicek & S. González, 2021 |
| Carex congestiflora Reznicek & S. González, 1999 |
| Carex consors C.B. Clarke, 1908 |
| Carex conspecta Mack., 1935 |