| Leucaena pueblana Britton & Rose, 1928 |
| Leucaena pulverulenta (Schltdl.) Benth., 1842 |
| Leucaena purpusii Britton & Rose, 1928 |
| Leucaena retusa Benth., 1852 |
| Leucaena shannonii Donn. Sm., 1914 |
| Leucaena sonorensis Britton & Rose, 1928 |
| Leucaena trichandra (Zucc.) Urb., 1900 |
| Leucaena x mixtec C.E. Hughes & S.A. Harris, 1998 |
| Leucaena x spontanea C.E. Hughes & S.A. Harris, 1998 |
| Leycephyllum Piper, 1924 |
| Leycephyllum micranthum Piper, 1924 |
| Libidibia (DC.) Schltdl., 1830 |
| Libidibia coriaria (Jacq.) Schltdl., 1830 |
| Libidibia paraguariensis (D. Parodi) G.P. Lewis, 2008 |
| Libidibia sclerocarpa (Standl.) Britton & Rose, 1930 |
| Liebrechtsia De Wild., 1902 |
| Lipusa Alef., 1866 |
| Lipusa formosa (Kunth) Alef., 1866 |
| Lipusa multiflora Alef., 1866 |
| Lojaconoa Bobrov, 1967 |