| Trifolium tridentatum Lindl., 1827 |
| Trifolium ultramontanum Greene, 1897 |
| Trifolium umbellatum Ser., 1825 |
| Trifolium variegatum Nutt., 1838 |
| Trifolium variegatum var. variegatum Nutt., 1838 |
| Trifolium wigginsii J.M. Gillett, 1976 |
| Trifolium willdenovii Spreng., 1826 |
| Trifolium wormskioldii Lehm., 1825 |
| Trifolium wormskioldii var. longicaule (Wooton & Standl.) L.D. Benson, 1941 |
| Trifolium wormskioldii var. ortegae (Greene) Barneby, 1989 |
| Ulex L., 1753 |
| Ulex europaeus L., 1753 |
| Vachellia Wight & Arn., 1834 |
| Vachellia biaciculata (S. Watson) Seigler & Ebinger, 2006 |
| Vachellia bilimekii (J.F. Macbr.) Seigler & Ebinger, 2006 |
| Vachellia brandegeana (I.M. Johnst.) Seigler & Ebinger, 2006 |
| Vachellia bravoensis (Isely) Seigler & Ebinger, 2006 |
| Vachellia californica (Brandegee) Seigler & Ebinger, 2006 |
| Vachellia campechiana (Mill.) Seigler & Ebinger, 2006 |
| Vachellia campechiana f. houghii (Britton & Rose) Seigler & Ebinger, 2006 |