| Ruellia pratensis D.N. Gibson, 1972 |
| Ruellia pringlei Fernald, 1907 |
| Ruellia puberula (Leonard) Tharp & F.A. Barkley, 1949 |
| Ruellia pulcherrima T. Anderson ex Hemsl., 1882 |
| Ruellia rosea (Nees) Hemsl., 1882 |
| Ruellia rubicaulis Cav., 1799 |
| Ruellia runyonii Tharp & F.A. Barkley, 1949 |
| Ruellia sarukhaniana Ramamoorthy, 1988 |
| Ruellia simplex C. Wright, 1869 |
| Ruellia sororia Standl., 1926 |
| Ruellia speciosa (Nees) Lindau, 1895 |
| Ruellia spissa Leonard, 1938 |
| Ruellia stemonacanthoides (Oerst.) Hemsl., 1882 |
| Ruellia tuberosa L., 1753 |
| Ruellia tuberosa var. occidentalis A. Gray, 1878 |
| Ruellia tubiflora Kunth, 1818 |
| Ruellia tubiflora var. parviflora Leonard, 1951 |
| Ruellia tuxtlensis Ramamoorthy & Hornelas, 1988 |
| Ruellia tweedii (Nees) T. Anderson ex Morong & Britton, 1893 |
| Ruellia yucatana (Leonard) Tharp & F.A. Barkley, 1949 |