| Muhlenbergia lucida Swallen, 1936 |
| Muhlenbergia lycuroides Vasey ex Beal, 1896 |
| Muhlenbergia macrotis (Piper) Hitchc., 1935 |
| Muhlenbergia macroura (Kunth) Hitchc., 1935 |
| Muhlenbergia madrensis M.E. Jones, 1912 |
| Muhlenbergia magna Hitchc., 1935 |
| Muhlenbergia majalcensis P.M. Peterson, 1989 |
| Muhlenbergia marshii I.M. Johnst., 1943 |
| Muhlenbergia matudae Sohns, 1956 |
| Muhlenbergia metcalfei M.E. Jones, 1912 |
| Muhlenbergia mexicana (L.) Trin., 1824 |
| Muhlenbergia meziana Hitchc., 1935 |
| Muhlenbergia michisensis Y. Herrera & P.M. Peterson, 1992 |
| Muhlenbergia microsperma (DC.) Kunth, 1829 |
| Muhlenbergia microsperma (DC.) Trin., 1824 |
| Muhlenbergia minutiflora (Michx.) Hitchc., 1896 |
| Muhlenbergia minutissima (Steud.) Swallen, 1947 |
| Muhlenbergia montana (Nutt.) Hitchc., 1920 |
| Muhlenbergia monticola Buckley, 1862 |
| Muhlenbergia mucronata (Kunth) Trin., 1824 |