| Croton masonii I.M. Johnst., 1931 |
| Croton mayanus B.L. León & Vester, 2006 |
| Croton mazapensis Lundell, 1942 |
| Croton mazapensis var. obtusifolius (Müll. Arg.) G.L. Webster, 2001 |
| Croton mcvaughii G.L. Webster, 2001 |
| Croton meissneri Müll. Arg., 1866 |
| Croton mexicanus Müll. Arg., 1865 |
| Croton mexicanus var. glabrescens Müll. Arg., 1865 |
| Croton mexicanus var. glandulosus Müll. Arg., 1865 |
| Croton mexicanus var. subintegrifolius Müll. Arg., 1865 |
| Croton michaelii V.W. Steinm., 2000 |
| Croton millspaughii Standl., 1930 |
| Croton miquelensis A.M. Ferguson, 1901 |
| Croton miradorensis Müll. Arg., 1866 |
| Croton mohavensis (A.M. Ferguson) Tidestr., 1935 |
| Croton monanthogynus Michx., 1803 |
| Croton morifolius Willd., 1805 |
| Croton morifolius var. genuinus Müll. Arg., 1865 |
| Croton morifolius var. lanatus Müll. Arg., 1866 |
| Croton morifolius var. obtusifolius Müll. Arg., 1865 |