Small hop clover T. dubium Sibth.
Large hop clover T. campestre Schreb.
Hop clover T. agrarium L.
Source: Magness et al. 1971
All three species of hop clovers are of European and Asia Minor origin and apparently came to the United States in mixtures of other seeds. The small and large hop clovers are adapted as winter annuals in the Southem and Pacific States. They occur in pastures and lawns and are valuable for winter and early spring pasture, being highly nutritious. Stems are small, reaching up to 18 inches. The two species are quite similar but the large hop clover is somewhat larger and higher yielding.
Hop clover, T. agrarium, occurs somewhat sparingly, mainly in northern states. It is not seeded but is valuable in grassland pastures where present.