| Reimarochloa oligostachya (Munro ex Benth.) Hitchc., 1909 |
| Rendlia Chiov., 1914 |
| Rettbergia Raddi, 1823 |
| Rhachidospermum Vasey, 1890 |
| Rhachidospermum mexicanum Vasey, 1890 |
| Rhampholepis Stapf, 1917 |
| Rhaphis Lour., 1790 |
| Rhaphis (Lour.) Roberty, 1960 |
| Rhaphis halepensis (L.) Roberty, 1954 |
| Rhaphis nutans (L.) Roberty, 1954 |
| Rhaphis zizanioides (L.) Roberty, 1954 |
| Rhipidocladum McClure, 1973 |
| Rhipidocladum barbinode Ruiz-Sanchez, C.D. Tyrrell & Vigosa, 2021 |
| Rhipidocladum bartlettii (McClure) McClure, 1973 |
| Rhipidocladum martinezii Davidse & R.W. Pohl, 1992 |
| Rhipidocladum pittieri (Hack.) McClure, 1973 |
| Rhipidocladum racemiflorum (Steud.) McClure, 1973 |
| Rhipidocladum zoqueorum Ruiz-Sanchez & C.D. Tyrrell & Sosa, 2019 |
| Rhombolytrum Link, 1833 |
| Rhombolytrum albescens (Vasey) Nash, 1901 |