REPRODUCTIVE ECOLOGY OF SAXIFRAGA-OPPOSITIFOLIA - PHENOLOGY, MATING SYSTEM, AND REPRODUCTIVE SUCCESS

We studied the reproductive biology in Saxifraga oppositifolia L. (Saxifragaceae) at a subarctic-alpine tundra site at Latnjajaure Field Station, North Swedish Lapland. Saxifraga oppositifolia is a perennial herb with circumpolar distribution, and it is one of the earliest flowering species in its habitats. Late-flowering genets were found to have accelerated phenology; this was correlated with heat acumulation per day. Individual flowers were found to last for 11.7 d. Strongly protogynous flowers (female phase lasted 4.2 d), declining stigma receptivity at the time of anther dehiscence, and more or less simultaneous flowering within genets reduce the probability for self-pollination. High seed abortion in naturally pollinated flowers (seed:ovule ratio = 0.25) supports this prediction. Crossing experiments showed that seed set is very low from autodeposition of pollen, and almost as low from selfing. Reproductive success was found to be pollen limited.