For several decades botanists have been impressed by the discovery that the distribution of secondary plant substances follows the general lines of plant relationships. However, it soon became clear that little was to be gained from the study of individual compounds and their natural distribu tion. Therefore, more comprehensive studies were attempt ed in which the secondary chemistry of a major plant group was carefully studied and evaluated in the broader context of comparative phytochemistry. Holger Erdtman's admir able work on Coniferae is the foremost example of this kind. Since then,...