| Coleosanthus wislizenii (A. Gray) Kuntze, 1891 |
| Coleosanthus wootonii Greene, 1897 |
| Colobogyne Gagnep., 1920 |
| Comaclinium Scheidw. & Planch., 1852 |
| Comaclinium aurantiacum Scheidw. & Planch., 1852 |
| Comaclinium montanum (Benth.) Strother, 1986 |
| Complaya Strother, 1991 |
| Conoclinium DC., 1836 |
| Conoclinium betonicifolium (Mill.) R.M. King & H. Rob., 1970 |
| Conoclinium betonicifolium var. betonicifolium (Mill.) R.M. King & H. Rob., 1970 |
| Conoclinium betonicifolium var. integrifolium (A. Gray) Patt., 2005 |
| Conoclinium betonicum DC., 1836 |
| Conoclinium dissectum A. Gray, 1852 |
| Conoclinium gonzaleziae E.E. Schill. & Panero, 2019 |
| Conoclinium greggii (A. Gray) Small, 1903 |
| Conoclinium ianthinum Morren, 1849 |
| Conoclinium integrifolium (A. Gray) Small, 1903 |
| Conoclinium macrocephalum (Less.) DC. ex B.L. Turner, 1997 |
| Conoclinium mayfieldii T.F. Patt., 1996 |
| Conyza Less., 1832 |