Pollen flavonoid studies provide useful information for evaluation of the nutritional and medicinal quality of natural honeys. In this study, pollen flavonoids of four Iranian Trifolium taxa are reported for the first time. Results have shown that all four studied taxa contain rutin, flavonoid sulphates, flavone C and C-/O-glycosides in their pollen. Morin is reported for the first time in the pollen of all studied taxa, with the exception of T. tumens. Apigenin, kaempferol, loteulin, myricetin, tricin, and vitexin were absent in the pollen of all studied species, but the pollen of T. fragiferum had quercetin. Flower pollen flavonoids are identical to those of the corresponding bee pollen confirming their use as chemical marker so important in ecology, pollination, honey qualification and preventing its adulteration.
