| Carex bolanderi Olney, 1868 |
| Carex boliviensis van Heurck & Müll. Arg., 1870 |
| Carex boliviensis subsp. boliviensis van Heurck & Müll. Arg., 1870 |
| Carex boliviensis subsp. occidentalis Reznicek & S. González, 2001 |
| Carex bonplandii Kunth, 1837 |
| Carex brachycalama Griseb., 1879 |
| Carex breedlovei Reznicek & S. González, 2025 |
| Carex brevior (Dewey) Mack., 1915 |
| Carex bromoides Willd., 1805 |
| Carex brunnipes Reznicek, 1986 |
| Carex cabralii Reznicek & S. González, 2021 |
| Carex caeligena Reznicek, 1990 |
| Carex camporum Mack., 1910 |
| Carex capitata L., 1759 |
| Carex catrina Lois, Jim. Mejías, Acedo, S. González & Reznicek, 2025 |
| 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 |