Printed in Great Britain. Pergamon Press Ltd. Evolution of Sesquiterpene Lactones in Angiosperms*

oxidation state; biochemical evolution. AJ~t~act--The paper attempts to discover an outline Of the evolutionary tmnde of seScluiterpene lactones in angiosperms. The working method involves the quantification Of skeletal specialization and oxidelJon state of the compounds and the assignment of evolutionary advancement indices, based on such date, to texa. In the angiosperms as a whole, sesquitarpene lactone evolution proceeds by divemification of structural types and by amplification of the oxidation state of the molecules. The opposite trend appears to operate at lower hierarchical level, in the Asteracese. In this family, which contains most of the known compounds of the class, sescluiterpene lactone evolution follows two parallel pathways in the tribes belonging to two groups of the subfamily Aster-oideae