| Carex meadii Dewey, 1842 |
| Carex melanosperma Liebm., 1850 |
| Carex mesophila Reznicek & S. González, 2021 |
| Carex mexicana J. Presl & C. Presl, 1828 |
| Carex michoacana Reznicek, Hipp & S. González, 2007 |
| Carex microptera Mack., 1909 |
| Carex microrhyncha Mack., 1913 |
| Carex monticola Boeckeler, 1881 |
| Carex muhlenbergii Kunth ex Boott, 1862 |
| Carex muhlenbergii var. xalapensis (Kunth) Britton, 1894 |
| Carex muriculata F.J. Herm., 1949 |
| Carex nigromarginata Schwein., 1824 |
| Carex nigromarginata f. minor Boeckeler, 1881 |
| Carex novogaliciana Reznicek, 1990 |
| Carex oaxacana L.H. Bailey, 1898 |
| Carex occidentalis L.H. Bailey, 1889 |
| Carex oerstedii Liebm., 1850 |
| Carex olivacea Liebm., 1850 |
| Carex oreocharis Holm, 1900 |
| Carex orizabae Liebm., 1850 |