| Olyra strictiflora (E. Fourn.) Hemsl., 1885 |
| Olyra surinamensis Hochst. ex Steud., 1855 |
| Olyra yucatana Chase, 1908 |
| Olyreae Kunth ex Spenn., 1825 |
| Olyrinae Kromb., 1875 |
| Ophiuros Gaertn., 1805 |
| Ophiuros cylindricus (Willd.) P. Beauv., 1812 |
| Ophiuros exaltatus (L.) Kuntze, 1891 |
| Ophiuros incurvatus (L.) P. Beauv., 1812 |
| Opizia J. Presl, 1830 |
| Opizia bracteata McVaugh, 1983 |
| Opizia stolonifera J. Presl, 1830 |
| Oplismenus P. Beauv., 1807 |
| Oplismenus affinis Schult., 1824 |
| Oplismenus affinis var. humboldtianus U. Scholz, 1981 |
| Oplismenus africanus P. Beauv., 1810 |
| Oplismenus angustifolius E. Fourn., 1886 |
| Oplismenus aristulatus Burcham, 1948 |
| Oplismenus brasiliensis Raddi, 1823 |
| Oplismenus bromoides Baker, 1885 |