| Monerma monandra P. Beauv., 1812 |
| Monocera Elliott, 1816 |
| Monochaete Döll, 1878 |
| Monochaete (Döll) Pilg., 1956 |
| Monopogon J. Presl, 1830 |
| Monopogon avenaceus J. Presl, 1830 |
| Moorea Lem., 1855 |
| Moorea argentea (Nees) Lem., 1855 |
| Morronea Zuloaga & Scataglini, 2014 |
| Morronea arundinariae (Trin. ex E. Fourn.) Zuloaga & Scataglini, 2014 |
| Morronea cayoensis (Swallen) Zuloaga & Scataglini, 2014 |
| Morronea guatemalensis (Swallen) Zuloaga & Scataglini, 2014 |
| Morronea incumbens (Swallen) Zuloaga & Scataglini, 2014 |
| Morronea parviglumis (Hack.) Zuloaga & Scataglini, 2014 |
| Morronea trichidiachnis (Döll) Zuloaga & Scataglini, 2014 |
| Moulinsia Raf., 1830 |
| Muantijamvella J.B. Phipps, 1964 |
| Muehlenbergia R. Hedw., 1806 |
| Muehlenbergia annua (Vasey) Swallen, 1947 |
| Muehlenbergia lanata (Kunth) Hitchc., 1935 |