| Cyperus parishii Britton, 1904 |
| Cyperus parryi Britton ex C.B. Clarke, 1908 |
| Cyperus patzcuarensis C.B. Clarke ex Kük., 1936 |
| Cyperus pedunculatus (R. Br.) J. Kern., 1958 |
| Cyperus penicillatus Conz., 1946 |
| Cyperus pennellii O'Neill & Ben. Ayers, 1944 |
| Cyperus perennis (M.E. Jones) O'Neill, 1945 |
| Cyperus perpusillus Boeckeler, 1868 |
| Cyperus phaeocephalus Griseb., 1874 |
| Cyperus phymatodes Muhl., 1817 |
| Cyperus piceus Liebm., 1850 |
| Cyperus piceus f. densior Kük., 1936 |
| Cyperus piceus f. potosiensis (C.B. Clarke) Kük., 1936 |
| Cyperus pittieri Boeckeler, 1896 |
| Cyperus planifolius Rich., 1792 |
| Cyperus planifolius f. decolorans Kük., 1936 |
| Cyperus planifolius var. brunneus (Sw.) Kük., 1926 |
| Cyperus planifolius var. ottonis (Boeckeler) Kük., 1926 |
| Cyperus platystachyus Griseb., 1864 |
| Cyperus polycephalus Lam., 1791 |