| Scirpus pachystylus C. Wright, 1871 |
| Scirpus pacificus Britton ex Parish, 1905 |
| Scirpus pallidus (Britton) Fernald, 1906 |
| Scirpus paludosus A. Nelson, 1899 |
| Scirpus paradoxus (Spreng.) Boeckeler, 1870 |
| Scirpus parvulus Roem. & Schult., 1817 |
| Scirpus pendulus Muhl., 1813 |
| Scirpus plantagineus Sw., 1797 |
| Scirpus plicarhachis Griseb., 1866 |
| Scirpus potosiensis C.B. Clarke, 1908 |
| Scirpus potosinus Britton, 1892 |
| Scirpus pringlei Britton, 1888 |
| Scirpus pungens Vahl, 1806 |
| Scirpus pungens var. pungens Vahl, 1806 |
| Scirpus pycnostachyus Salzm. ex Steud., 1855 |
| Scirpus radicans Poir., 1805 |
| Scirpus remireoides Griseb., 1874 |
| Scirpus reticulatus Lam., 1791 |
| Scirpus retroflexus Poir., 1804 |
| Scirpus riparius J. Presl & C. Presl, 1830 |