Reproductive phenology of Dicranum majus in central Norway

Shoots of Dicranum majus were collected monthly during the snow-free period from permanent plots to study the reproductive phenology in a boreal spruc e forest in central Norway. Numbers of sporophytes (current and previous ye ars), gametangia and dwarf males on each shoot and the reproductive stage o f gametangia and sporophytes were registered. Gametangia are Formed either in late autumn or in early spring, fertilization occurs in June and July an d spores are dispersed during August to October in the following year. Mature archegonia were present only during a restricted period (June-July) while mature antheridia were found throughout the summer and autumn. Dwarf males were found only in a region about one cm below the apex. There was no trace of old male gametophores below, indicating that gametophores a re annual. However, from this study it is not possible to conclude whether the gametophyte is annual or new males are formed through, for instance, pe rennial protonema. Fertilization frequency in the samples was high (75%), but the fertilizatio n frequency of the entire population is lower as the samples were taken fro m subpopulations that produce sporophytes frequently.