| Larrea jamesii (Torr. & A. Gray) Britton, 1930 |
| Larrea melanosticta (S. Schauer) Britton, 1930 |
| Larrea microphylla (Torr.) Britton, 1930 |
| Larrea montana Britton, 1930 |
| Larrea multijuga (S. Watson) Britton, 1930 |
| Larrea oxycarpa (Benth. ex A. Gray) Britton, 1930 |
| Larrea parryi (Fisher) Britton, 1930 |
| Larrea peninsularis Britton, 1930 |
| Larrea texensis (Fisher) Britton, 1930 |
| Larrea watsonii (Fisher) Britton, 1930 |
| Larrea wootonii Britton, 1930 |
| Lathyrus L., 1753 |
| Lathyrus alefeldii T.G. White, 1894 |
| Lathyrus americanus Mill., 1768 |
| Lathyrus arizonicus Britton, 1889 |
| Lathyrus arvensis Phil., 1856 |
| Lathyrus brachycalyx Rydb., 1907 |
| Lathyrus brachycalyx subsp. eucosmus (Butters & H. St. John) S.L. Welsh, 1966 |
| Lathyrus brachycalyx var. eucosmus (Butters & H. St. John) S.L. Welsh, 1978 |
| Lathyrus crassipes Gillies ex Hook. & Arn., 1833 |