| Carex tuxtleca Lois, Jim. Mejías, Acedo, S. González & Reznicek, 2025 |
| Carex ultra L.H. Bailey, 1886 |
| Carex umbellata Schkuhr ex Willdenow, 1805 |
| Carex underwoodii Britton, 1905 |
| Carex utriculata Boott, 1839 |
| Carex vallicola Dewey, 1861 |
| Carex vallicola var. hidalgensis F.J. Herm., 1960 |
| Carex venosivaginata Standl. & Steyerm., 1953 |
| Carex viridiflora Mack., 1935 |
| Carex viridis Schltdl. & Cham., 1831 |
| Carex vitrea Holm, 1904 |
| Carex vizarronensis Gómez-Sánchez, Cabrera-Luna, S. González & Reznicek, 2012 |
| Carex volcanica F.J. Herm., 1971 |
| Carex vulpinoidea Michx., 1803 |
| Carex wootonii Mack., 1915 |
| Carex xalapensis Kunth, 1837 |
| Carex xipetotecana Lois, Jim. Mejías, Acedo, S. González & Reznicek, 2025 |
| Cariceae Dumort., 1827 |
| Chaetocyperus Nees, 1834 |
| Chaetocyperus acicularis (L.) Nees, 1842 |