Xeric environments impose significant constraints on plant life histories.
In ferns, there is a strong correlation between the apomictic life cycle and drought-prone habitats. The life cycle of apomictic ferns involves modifications of both the sporophytic and gametophytic generations. Sporophytes have an altered sporogenetic process in which a premeiotic endomitosis results in chromosome duplication without cytokinesis. As such, spore mother cells have a doubled chromosome number, and meiosis produces spores with the same genetic composition as the original sporophyte. Gametophytes produced by these spores initiate sporophytes directly, without fertilization.