| Piper littorale C. DC., 1897 |
| Piper longepetiolatum (C. DC.) Trel., 1929 |
| Piper longispicum C. DC., 1908 |
| Piper lucaeanum Kunth, 1839 |
| Piper lundellii Trel., 1936 |
| Piper luxii C. DC., 1894 |
| Piper macrophyllum Kunth, 1816 |
| Piper macrostachyon Vahl, 1804 |
| Piper maculosum L., 1753 |
| Piper magnoliifolium Jacq., 1791 |
| Piper malpasoense Tebbs, 1993 |
| Piper marginatum Jacq., 1790 |
| Piper marginecontinuum Callejas, 2020 |
| Piper martensianum C. DC., 1869 |
| Piper matudae Lundell, 1941 |
| Piper maxonii C. DC., 1920 |
| Piper mcvaughii Bornst., 1989 |
| Piper medium Jacq., 1781 |
| Piper melanocladum C. DC., 1920 |
| Piper melanostictum (Miq.) C. DC., 1869 |