| Carex chordalis Liebm., 1850 |
| Carex ciliaris Fernald, 1907 |
| Carex cochranei Reznicek, 1993 |
| Carex comolaflor Lois, Jim. Mejías, Acedo, S. González & Reznicek, 2025 |
| 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 |
| Carex cooleyi Dewey, 1845 |
| Carex cortesii Liebm., 1850 |
| Carex coulteri Boott ex Hemsl., 1885 |
| Carex curviculmis Reznicek, 1993 |
| Carex dentata Reznicek & S. González, 2021 |
| Carex diandra Schrank, 1781 |
| Carex diehlii M.E. Jones ex F.J. Herm., 1954 |
| Carex distentiformis F.J. Herm., 1971 |
| Carex donnell-smithii L.H. Bailey, 1889 |