Physio-Ecological Factors Relating to Reproduction and Phenology in Fontinalis dalecarlica

Fontinalis dalecarlica BSG from North Carolina was studied to determine the effects of photoperiod and exposure to air on archegonial production, growth, branching and rhizoids in order to develop a preliminary model for phenology. Mosses were cultured for 16 weeks in four photoperiods at 8C and 1560 lux in artificial streams. The North Carolina population of Fontinalis dalecarlica is a quantitative short day plant and produced archegonia first in the 6 hr light/18 hr dark photopheriod, but in longer photoperiods had produced an equal number by the end of 16 weeks. Long photoperiods favored growth, branching and rhizoids. Reduced growth and branching in the longest photoperiod (18 hr light/6 hr dark) suggests that light inhibition may occur on longer days. Aerated mosses produce more archegonia than submersed mosses. These observations suggest that the moss is adapted to fluctuating water levels by dispersing its gametes while the water level is low. These experiments provide a model for the timing and mechanisms of sperm dispersal that can now be tested in nature. The genus Fontinalis Hedw. has been used fre- quently in physiological studies as a representative aquatic plant (Blackman & Smith 1910; Steemann Nielsen 1947); it has been represented in many pol- lution studies (Frahm 1974; Sodergren 1976; Bur- ton & Peterson 1979); and it is widely distributed in the north temperate region. Its large size and relative abundance further support its choice for detailed biological study. The present study pro- vides a suggested phenological model to serve as a