| Trifolium nelsonii House, 1906 |
| Trifolium olivaceum Greene, 1887 |
| Trifolium ortegae Greene, 1897 |
| Trifolium ortegae f. pumilum Vaughan, 1939 |
| Trifolium oxypetalum Fisch. & C.A. Mey., 1845 |
| Trifolium palmeri S. Watson, 1876 |
| Trifolium pinetorum Greene, 1894 |
| Trifolium potosanum Lojac., 1883 |
| Trifolium pratense L., 1753 |
| Trifolium reflexum L., 1753 |
| Trifolium reflexum var. reflexum L., 1753 |
| Trifolium repens L., 1753 |
| Trifolium repens var. giganteum Lagr.-Foss., 1847 |
| Trifolium rhombeum S. Schauer, 1847 |
| Trifolium roseum D.Heller & Zohary, 1984 |
| Trifolium rusbyi Greene, 1887 |
| Trifolium saxicolum Small, 1894 |
| Trifolium schiedeanum S. Watson, 1882 |
| Trifolium schneideri Standl., 1940 |
| Trifolium sonorense T.K. Ahlq. & Vincent, 2018 |