Achillea millefolium contains phenolic compounds such as dicaffeoylquinic acids and flavonoids causing choleretic and spasmolytic effects contains. The flavonoids mainly occur as mono- and diglycosides of apigenin, luteolin, quercetin, rutin, centaureidin, casticin, acacetin, isorhamnetin and artemetin.
As you can see, what I gave you as flavonoids is a synthesis of several ancient and recent articles. And as Carol has shown, the composition of Achillea millefolium in flavonoids varies according to several ecological and other parameters.