| Clappia suaedifolia A. Gray, 1858 |
| Clappiinae H. Rob., 1978 |
| Clavigera DC., 1836 |
| Clavigera brachyphylla A. Gray, 1848 |
| Clavigera corymbosa DC., 1836 |
| Clavigera scabra Benth., 1839 |
| Clavigera scoparia DC., 1836 |
| Clavigera spinulosa A. Gray, 1848 |
| Cleanthes D. Don, 1830 |
| Clibadium L., 1771 |
| Clibadium arboreum Donn. Sm., 1889 |
| Clibadium donnell-smithii J.M. Coult., 1891 |
| Clibadium oligandrum S.F. Blake, 1937 |
| Clibadium pueblanum S.F. Blake, 1924 |
| Clibadium surinamense L., 1771 |
| Clomenocoma Cass., 1816 |
| Clomenocoma aurantia (L.) Cass., 1817 |
| Clomenocoma grandiflora Rydb., 1915 |
| Clomenocoma montana Benth., 1841 |
| Clomenocoma pinnata (Cav.) DC., 1836 |