Localization of chromenes and benzofurans in the genus Encelia (Asteraceae)

Phytochemical and microscopial analysis of leaves and stems of various species of Encelia showed a strict correlation between the presence of resin ducts and the accumulation of benzopyrans and benzofurans. Fluorescence microscopy of Encelia farinosa proved unambigously that these compounds are stored exclusively in the resin ducts and the surrounding cells.