| Ormosia isthmensis Standl., 1937 |
| Ormosia macrocalyx Ducke, 1922 |
| Ormosia macrophylla Benth., 1837 |
| Ormosia mexicana Standl., 1922 |
| Ormosia oaxacana Rudd, 1981 |
| Ormosia panamensis Benth. ex Seem., 1853 |
| Ormosia schippii Pierce ex Standl. & Steyerm., 1946 |
| Ormosia toledoana Standl., 1935 |
| Ormosia velutina Rudd, 1960 |
| Orobus L., 1753 |
| Orobus arborescens Sessé & Moc., 1889 |
| Orobus argenteus Mill., 1759 |
| Orobus diffusus Nutt., 1813 |
| Orobus dissitifolius Alef., 1861 |
| Orobus faba Brot., 1804 |
| Orobus polymorphus (Nutt.) Alef., 1861 |
| Orobus sericeus Sessé & Moc., 1890 |
| Orobus trifoliatus Sessé & Moc., 1894 |
| Orobus vestitus (Nutt.) Alef., 1861 |
| Otholobium C.H. Stirt., 1981 |