| Carex lagunensis M.E. Jones, 1933 |
| Carex lanuginosa Michx., 1803 |
| Carex lasiocarpa Ehrh., 1784 |
| Carex lasiocarpa var. americana Fernald, 1942 |
| Carex latebrosa Mack., 1907 |
| Carex lativena S.D. Jones & G.D. Jones, 1993 |
| Carex lenticularis Michx., 1803 |
| Carex leporina L., 1753 |
| Carex leporina var. bracteata Liebm., 1850 |
| Carex leptalea Wahlenb., 1803 |
| Carex leptopoda Mack., 1917 |
| Carex leucodonta Holm, 1903 |
| Carex liebmannii Walp., 1852 |
| Carex lithosperma (L.) J.F. Gmel., 1791 |
| Carex longicaulis Boeckeler, 1882 |
| Carex longicaulis var. coulteri (W. Boott ex Hemsl.) Kük., 1909 |
| Carex longii Mack., 1922 |
| Carex longiligula Reznicek & S. González, 2001 |
| Carex longissima M.E. Jones, 1933 |
| Carex lupulina Muhl. ex Willd., 1805 |