We trace the development of our understanding regarding the mating systems of moonworts (i.e., Botrychium sensu stricto), from the early recognition of inbreeding as the primary mode of sexual reproduction to the discovery of predominantly outcrossing populations in high mountain habitats. We propose an evolutionary trajectory in which both mating systems, in concert with mycorrhizal support, have been able to sustain Botrychium populations through changing environments. We present a depiction of the fern life cycle that portrays the positive role of inbreeding in speciation and evolution of Botrychium and its relevance to ferns and lycophytes in general.