| Muhlenbergia appressa C.O. Goodd., 1941 |
| Muhlenbergia arachnoidea Trin. ex Kunth, 1833 |
| Muhlenbergia arenacea (Buckley) Hitchc., 1928 |
| Muhlenbergia arenicola Buckley, 1862 |
| Muhlenbergia argentea Vasey, 1886 |
| Muhlenbergia aristulata Rydb., 1905 |
| Muhlenbergia arizonica Scribn., 1888 |
| Muhlenbergia arsenei Hitchc., 1928 |
| Muhlenbergia articulata Scribn., 1891 |
| Muhlenbergia aspera Trin. ex Kunth, 1833 |
| Muhlenbergia aspericaulis Nees ex Trin., 1840 |
| Muhlenbergia asperifolia (Nees & Meyen ex Trin.) Matthei, 1984 |
| Muhlenbergia asperifolia (Nees & Meyen ex Trin.) Parodi, 1928 |
| Muhlenbergia berlandieri Trin., 1841 |
| Muhlenbergia berteroniana (Schult.) Kunth, 1829 |
| Muhlenbergia beyrichiana Kunth, 1833 |
| Muhlenbergia biloba Hitchc., 1913 |
| Muhlenbergia botteri E. Fourn., 1886 |
| Muhlenbergia bourgeaei E. Fourn., 1885 |
| Muhlenbergia brandegeei C. Reeder, 1956 |