| Carex hirtella (Sw.) J.F. Gmel., 1791 |
| Carex huehueteca Standl. & Steyerm., 1947 |
| Carex hultenii Aspl., 1954 |
| Carex humboldtiana Steud., 1855 |
| Carex hystericina Muhl. ex Willd., 1805 |
| Carex hystericina var. underwoodii (Britton) Kük., 1909 |
| Carex interior L.H. Bailey, 1893 |
| Carex interior f. keweenawensis (F.J. Herm.) Fernald, 1942 |
| Carex interior var. keweenawensis F.J. Herm., 1941 |
| Carex interjecta Reznicek, 1993 |
| Carex involucrata Boeckeler, 1855 |
| Carex involucratella Mack., 1931 |
| Carex ixtapalucensis S. González ex Reznicek, 1986 |
| Carex jamesonii Boott, 1845 |
| Carex jamesonii var. chordalis (Liebm.) Kük., 1909 |
| Carex jamesonii var. gracilis L.H. Bailey, 1888 |
| Carex jamesonii var. melanosperma (Liebm.) Kük., 1909 |
| Carex jovis C.B. Clarke, 1908 |
| Carex kelloggii W. Boott, 1880 |
| Carex kelloggii var. kelloggii W. Boott, 1880 |