| bulgaria | | carex nigra subsp. nigra | subspecies | 3 | 0 |
| canada | | carex nigra subsp. nigra | subspecies | 3 | 0 |
| canada | nova scotia | carex nigra | species | 1 | 0 |
| canada | quebec | carex nigra | species | 6 | 0 |
| finland | | carex nigra subsp. juncella | subspecies | 1 | 0 |
| france | | carex nigra | species | 2 | 0 |
| germany | | carex nigra | species | 1 | 0 |
| greece | | carex nigra subsp. nigra | subspecies | 3 | 0 |
| greenland | | carex nigra subsp. nigra | subspecies | 3 | 0 |
| netherlands | | carex nigra subsp. nigra | subspecies | 3 | 0 |
| norway | | carex nigra subsp. juncella | subspecies | 3 | 0 |
| norway | akershus county | carex nigra subsp. juncella | subspecies | 2 | 0 |
| portugal | | carex nigra | species | 2 | 0 |
| russia | | carex nigra subsp. nigra | subspecies | 6 | 0 |
| spain | | carex nigra | species | 2 | 0 |
| spain | | carex nigra subsp. nigra | subspecies | 6 | 0 |
| sweden | | carex nigra | species | 1 | 0 |
| sweden | | carex nigra subsp. nigra | subspecies | 6 | 0 |
| switzerland | | carex nigra | species | 67 | 0 |
| switzerland | | carex nigra subsp. nigra | subspecies | 1 | 0 |
| turkey | | carex nigra subsp. nigra | subspecies | 3 | 0 |
| united kingdom | | carex nigra | species | 6 | 0 |
| united kingdom | scotland | carex nigra | species | 1 | 0 |