| Piper indignum Trel., 1929 |
| Piper instabilipes Trel., 1937 |
| Piper ixocubvainense Standl. & Steyerm., 1952 |
| Piper ixtlanense Callejas, 2020 |
| Piper jacquemontianum Kunth, 1839 |
| Piper jalapense M. Martens & Galeotti, 1843 |
| Piper jalapense (Miq.) C. DC., 1869 |
| Piper jaliscanum S. Watson, 1891 |
| Piper karwinskianum (Kunth) Kunth ex C. DC., 1869 |
| Piper kerberi C. DC., 1898 |
| Piper kunthii (Miq.) C. DC., 1869 |
| Piper lacunosum Kunth, 1816 |
| Piper lanceifolium Kunth, 1816 |
| Piper lanceolatum Ruiz & Pav., 1798 |
| Piper lapathifolium (Kunth) Steud., 1841 |
| Piper laurifolium Mill., 1768 |
| Piper lepturum Kunth, 1839 |
| Piper leucophyllum (Miq.) C. DC., 1869 |
| Piper liebmannii C. DC., 1872 |
| Piper lindenii (Miq.) C. DC., 1869 |