| Piper purpusianum Trel., 1926 |
| Piper purulhanum C. DC., 1920 |
| Piper quadrifolium L., 1762 |
| Piper realgoanum C. DC., 1872 |
| Piper reflexum L. f., 1781 |
| Piper rohrii C. DC., 1869 |
| Piper rosei C. DC., 1920 |
| Piper rotundifolium L., 1753 |
| Piper rovirosae C. DC., 1920 |
| Piper rugosum Lam., 1791 |
| Piper sancti-felicis Trel., 1927 |
| Piper sanctum (Miq.) Schltdl. ex C. DC., 1869 |
| Piper sarculatum (Trel.) Callejas, 2020 |
| Piper saurodermus Ortiz-Rodr. & J.R. Carral, 2025 |
| Piper scabrum Lam., 1791 |
| Piper scalarispicum Trel., 1938 |
| Piper schiedeanum Steud., 1841 |
| Piper schippianum Trel. & Standl., 1952 |
| Piper schlechtendalianum (Miq.) C. DC., 1869 |
| Piper schlechtendalii Steud., 1841 |