| Muhlenbergia peruviana var. elatior Kuntze, 1898 |
| Muhlenbergia peruviana var. peruviana (P. Beauv.) Steud., 1840 |
| Muhlenbergia peruviana var. pulvinata (Nees) Nees & E. Mey. ex Kuntze, 1898 |
| Muhlenbergia peruviana var. subcaespitosa Kuntze, 1898 |
| Muhlenbergia phalaroides (Kunth) P.M. Peterson, 2009 |
| Muhlenbergia phleoides (Kunth) Columbus, 2010 |
| Muhlenbergia phragmitoides Griseb., 1874 |
| Muhlenbergia pilosa P.M. Peterson, Wipff & S.D. Jones, 1992 |
| Muhlenbergia plumbea (Trin.) Hitchc., 1913 |
| Muhlenbergia plumiseta Columbus, 2010 |
| Muhlenbergia polycaulis Scribn., 1911 |
| Muhlenbergia polypogon (DC.) Kunth, 1829 |
| Muhlenbergia polypogonoides Hack., 1902 |
| Muhlenbergia porteri Scribn., 1896 |
| Muhlenbergia presliana Hitchc., 1935 |
| Muhlenbergia pringlei (Scribn.) Scribn., 1892 |
| Muhlenbergia pubescens (Kunth) Hitchc., 1935 |
| Muhlenbergia pubigluma Swallen, 1943 |
| Muhlenbergia pulcherrima Scribn. ex Beal, 1896 |
| Muhlenbergia purpurea Nutt., 1848 |