Exudate flavonoids in Asteraceae from Arizona, California and Mexico

Abstract

A series of Asteraceae, belonging to the tribes Astereae, Eupatorieae, Helenieae and Heliantheae, have been analyzed for the presence of flavonoid aglycones accumulated on leaf and stem surfaces. Methyl ethers of apigenin, luteolin, kaempferol, and quercetin as well as methyl ethers of their relevant 6-hydroxy derivatives were abundant, whereas 8-O-substituted derivatives and flavanones were encountered only occasionally: 6,8-di-O-substituted flavonols were found in only one species.