ABSTRACT
Bryophytes are unique among land plants in that the gametophyte generation is photosynthetically dominant, with the sporophyte permanently attached to and partially parasitic upon the gametophyte. It is therefore convenient to consider the process of sexual reproduction as beginning with the development of gametangia upon the gametophyte and proceeding through gametangial maturation, fertilization, sporophyte development, and sporogenesis to the release of spores. There have been two main phases in studies of seasonal patterns of reproductive development. In early investigations a number of authors reported dates of fertilization and spore release in a wide range of European and North American mosses. The environmental factors controlling the different phases of development are likely to vary between species. However, common features sometimes may be detected among groups of species occupying particular habitats or showing similar patterns of geographical distribution. Reproductive phenology in several widely ranging species has been compared in temperate, boreal forest, and polar localities.
