| Muhlenbergia involuta Swallen, 1932 |
| Muhlenbergia iridifolia Soderstr., 1967 |
| Muhlenbergia jaime-hintonii P.M. Peterson & Valdés-Reyna, 1999 |
| Muhlenbergia jaliscana Swallen, 1958 |
| Muhlenbergia lanata (Kunth) Hitchc., 1937 |
| Muhlenbergia laxa Hitchc., 1935 |
| Muhlenbergia laxiflora Scribn., 1894 |
| Muhlenbergia lemmonii Scribn., 1890 |
| Muhlenbergia leptoura (Piper) Hitchc., 1935 |
| Muhlenbergia liebmannii E. Fourn., 1886 |
| Muhlenbergia ligulata (E. Fourn.) Scribn. & Merr., 1901 |
| Muhlenbergia lindheimeri Hitchc., 1934 |
| Muhlenbergia longifolia Vasey, 1893 |
| Muhlenbergia longiglumis Vasey, 1893 |
| Muhlenbergia longiligula Hitchc., 1934 |
| Muhlenbergia longiseta Benth., 1840 |
| Muhlenbergia lucida Swallen, 1936 |
| Muhlenbergia lycuroides Vasey ex Beal, 1896 |
| Muhlenbergia macrotis (Piper) Hitchc., 1935 |
| Muhlenbergia macroura (Kunth) Hitchc., 1935 |