I am sorry that I can't really point you towards good English books:( but incidentally, Serebryakov's Morphology of plants (from the sixties, I think) did start with an overview of dated theories, starting around Goethe; and he managed to write it logically and readably. (I think people should just accept that history of science is a discipline deserving popular books of it own, but so far, the best HoS stuff I'be come across was in introductions to pop-sci.) IMO at least the cutting-edge biology today is extremely 'model organism-oriented', which limits its applicability. (It also seems to me that you're not the kind of person to wish to learn about angiosperm evolution or archaeobacteriae from the deepest seas:) though I've read a cool monograph (1997, I think) on secondary metabolites in onion secreted when it is wounded, I can't say it is an introductory book. It has a section on plants' defences against infection... It's fascinating when you think 'wait, onions have mycorrhiza, and in other plants it was shown to influence the levels of sec. met. - I wonder how their results would change if...' But a layperson should be given the intro about onions in general - their observable properties, like smell when cut, and ability to keep well - maybe even their selection history (taxonomy of cultivated plants is often horribly convoluted.)