| Nissolia ruddiae Cruz Durán & M. Sousa, 2004 |
| Nissolia schottii (Torr.) A. Gray, 1861 |
| Nissolia setosa Brandegee, 1891 |
| Nissolia uniflora Moench, 1760 |
| Nissolia wislizeni (A. Gray) A. Gray, 1861 |
| Odonia Bertol., 1822 |
| Odonia incana Rose, 1906 |
| Odonia viridiflora Rose, 1906 |
| Olivianae Krukoff & Barneby, 1974 |
| Olneya A. Gray, 1854 |
| Olneya tesota A. Gray, 1854 |
| Ononis L., 1753 |
| Ononis crotalarioides M.E. Jones, 1929 |
| Orbexilum Raf., 1832 |
| Orbexilum chiapasanum B.L. Turner, 2007 |
| Orbexilum melanocarpum (Benth. ex Hemsl.) Rydb., 1919 |
| Orbexilum oliganthum (Brandegee) B.L. Turner, 2007 |
| Ormosia Jack., 1811 |
| Ormosia apulensis Cortés, 1919 |
| Ormosia carinata N. Zamora, 2006 |