| Trifolium hickeyi T.K. Ahlq. Vincent, 2020 |
| Trifolium inconspicuum (Fernald) A. Heller, 1906 |
| Trifolium insularum P.B. Kenn., 1913 |
| Trifolium involucratum Ortega, 1797 |
| Trifolium lacerum Greene, 1894 |
| Trifolium longicaule Wooton & Standl., 1913 |
| Trifolium longifoliolum (Hemsl.) House, 1906 |
| Trifolium longifolium House, 1906 |
| Trifolium lozani House, 1906 |
| Trifolium macraei Hook. & Arn., 1833 |
| Trifolium macraei var. albopurpureum (Torr. & A. Gray) Greene, 1891 |
| Trifolium macrorrhizum Ulbr., 1906 |
| Trifolium mathewsii A. Gray, 1854 |
| Trifolium melananthum Hook. & Arn., 1838 |
| Trifolium melilotus L., 1753 |
| Trifolium melilotus var. officinalis L., 1753 |
| Trifolium mexicanum Hemsl., 1879 |
| Trifolium microcephalum Pursh, 1814 |
| Trifolium microcephalum f. velutinum McDermott, 1910 |
| Trifolium microcephalum var. lemmonii Lojac., 1883 |