Conifer Reproductive Biology

When it comes to reproduction, gymnosperms are deeply weird. Cycads and co- fers have drawn out reproduction: at least 13 genera take over a year from polli- tion to fertilization. Since they don’t apparently have any selection mechanism by which to discriminate among pollen tubes prior to fertilization, it is natural to w- der why such a delay in reproduction is necessary. Claire Williams’ book celebrates such oddities of conifer reproduction. She has written a book that turns the context of many of these reproductive quirks into deeper questions concerning evolution. The origins of some of these questions can be traced back Wilhelm Hofmeister’s 1851 book, which detailed the revolutionary idea of alternation of generations. This alternation between diploid and haploid generations was eventually to become one of the key unifying ideas in plant evolution. Dr. Williams points out that alter- tion of generations in conifers shows strong divergence in the evolution of male and female gametes, as well as in the synchronicity of male and female gamete development. How are these coordinated to achieve fertilization? Books on conifer reproduction are all too rare. The only major work in the last generation was Hardev Singh’s 1978 Embryology of Gymnosperms, a book that summarized the previous century’s work. Being a book primarily about embry- ogy, it stopped short of putting conifer reproduction in a genetic or evolutionary context.