| Columbiana Hitchc. & Chase, 1910 |
| Commelinidium Stapf, 1920 |
| Commutata Hitchc. & Chase, 1910 |
| Comopyrum Á. Löve, 1982 |
| Cornucopiae L., 1753 |
| Cornucopiae altissima Walter, 1788 |
| Cornucopiae hyemalis Walter, 1788 |
| Cornucopiae perennans Walter, 1788 |
| Cortaderia Stapf, 1897 |
| Cortaderia argentea (Nees) Stapf, 1897 |
| Cortaderia dioica Speg., 1902 |
| Cortaderia selloana (Schult. & Schult. f.) Asch. & Graebn., 1900 |
| Costia Willk., 1858 |
| Costia cristata (L.) Willk., 1858 |
| Cottea Kunth, 1829 |
| Cottea pappophoroides Kunth, 1829 |
| Cotteinae Reeder, 1965 |
| Craepalia Schrank, 1789 |
| Craepalia (Schrank) Dumort., 1823 |
| Critesion Raf., 1819 |