Are Ophioglossaceae really derived from coenopterid ferns? What is their relationship to other ferns? What is the origin of their morphological peculiarities? To what extent is morphology related to habitat and mycorrhizal associations? These questions have perplexed pteridologists for over a century of study of this enigmatic group of plants. In this presentation we introduce aspects of morphology, growth habit, and ecology that give rise to these questions. We also present overviews of the group's taxonomy, cytology, and phytogeography to set the stage for detailed presentations that follow. These studies illuminate the unique contributions of the Ophioglossaceae to the study of pteridophyte evolution and conservation.

Key words: Botrychium, Ophioglossaceae, Ophioglossum