XVI International Botanical Congess

Pollen grains production process started in upper devonian in the group of seed ferns and achieved perfection in gymno- and angiosperms. Only seed ferns, possesing easily stretching microspore wall (owing to different marginal ridges, lists, distal ectexina refinings, which made possible male gametophyte development inside of sporoderma) were ready for this evolutionary stage. Firrow appearance turned out to be successful, widely spread evolutionary event. At the same time different groups of seed plants developed specific sporoderma structures, providing volume changing without sporoderma rupture. It was also determined that each sporoderma lay and structure are multifunctional.