FLAVONOID DIVERSIFICATION IN THE ACHILLEA AGERATIFOLIA AND A. CLAVENNAE GROUPS (ASTERACEAE)

The Achillea ageratifolia and A. clavennae groups (Asteraceae, tribe Anthemideae) were investigated for intra‐ and interspecific leaf flavonoid variation. Numerous flavonoid glycosides, mostly unidentified, and variously methylated free aglycones based on scutellarein, 6‐hydroxyluteolin, quercetagetin, and 6‐hydroxy‐kaempferol were detected. The distribution of methylated aglycones among individuals of A. ageratifolia was used to model the putative biosynthetic pathways. Several steps in the biosynthesis probably involve enzymes (methyltransferases) with strict positional specificities and broader substrate specificities. Geographical patterns in the flavonoid content of A. ageratifolia were only partly consistent with the current concept of A. ageratifolia. Different flavonoid profiles in A. ageratifolia do not appear to be of crucial importance in its adaptation to different habitats. The species of the A. clavennae group were clearly separable on flavonoid profiles and the presence of a hybrid population was supported by the flavonoid data. Interspecific differences in number of glycosides in relation to the number of free aglycones are discussed.