| Odontadenieae Miers, 1878 |
| Orthosia Decne., 1844 |
| Orthosia angustifolia (Turcz.) Liede Meve, 2013 |
| Orthosia bonplandiana (Schult.) Liede & Meve, 2008 |
| Orthosia cynanchoides W.D. Stevens, 2005 |
| Orthosia glaberrima (Woodson) W.D. Stevens, 2005 |
| Orthosia guilleminiana (Decne.) Liede & Meve, 2008 |
| Orthosia kunthii Decne., 1844 |
| Orthosia misera (L.O. Williams) W.D. Stevens, 2005 |
| Orthosia pubescens (Greenm.) Liede & Meve, 2008 |
| Orthosia stipitata W.D. Stevens, 2005 |
| Orthosiinae Liede & Rapini, 2005 |
| Otaria Kunth, 1819 |
| Otaria auriculata (Kunth) G. Don, 1837 |
| Otaria fragrans Benth., 1842 |
| Oxypetalinae E. Fourn., 1878 |
| Oxypetalum R. Br., 1810 |
| Oxypetalum cordifolium (Vent.) Schltr., 1899 |
| Oxypetalum huilense Pittier, 1910 |
| Oxypetalum riparium Kunth, 1819 |