The known flavonoids apigenin, luteolin, 1μuteolin 7-O-β- d-glucoside, quercetin 3-O-β- d-glucoside, vitexin, isovitexin, vicenin-1, vicenin-2, swertisin, orientin, isoorientin, lucenin-1, lucenin-2, and swertia-japonin were identified as constituents of one or more of the five North American Tragopogon species. The distribution of these compounds is consistent with the genetic relationships between the species. A new C-glycosyl flavone, O-xylosylisovitexin, was detected in T. dubius.