| Lobelia pulchella Vatke, 1874 |
| Lobelia purpusii Brandegee, 1911 |
| Lobelia quiexobrae Rzed., 2018 |
| Lobelia ramosissima M. Martens & Galeotti, 1842 |
| Lobelia rensonii E. Wimm., 1935 |
| Lobelia rigidula Kunth, 1819 |
| Lobelia rosalindae Rzed., 2018 |
| Lobelia ruderalis Willd. ex Schult., 1819 |
| Lobelia rzedowskii Art. Castro & I. Gut., 2018 |
| Lobelia sartorii Vatke, 1874 |
| Lobelia sartorii var. piscinula (E. Wimm.) E. Wimm., 1953 |
| Lobelia saturninoi Art. Castro & I. Gut., 2018 |
| Lobelia schmitzii E. Wimm., 1929 |
| Lobelia scrobiculata E. Wimm., 1953 |
| Lobelia seleriana E. Wimm., 1935 |
| Lobelia setulosa E. Wimm., 1924 |
| Lobelia sinaloae Sprague, 1929 |
| Lobelia splendens Humb. & Bonpl. ex Willd., 1809 |
| Lobelia splendens f. ignea (Hook.) Voss, 1894 |
| Lobelia splendens var. atrosanguinea Hook., 1843 |