Temporal patterning of blooming phenology inPedicularison Mount Rainier

摘要

The temporal patterning of flowering of five sympatric species ofPedicularisin a subalpine meadow is documented. Two species bloom early in the growing season, one is intermediate, and two flower toward the later part of the season. The differences between species are related to the range of blooming periods (in days), the number of inflorescences at maximum bloom, and the time of peak bloom. No significant variation in flowering pattern occurred during the years of observation (1977, 1978, and 1979). More than 93 of the time individual bumblebees continued to forage on the samePedicularisspecies as was previously visited; yet when switches in the diet of the bees occurred, they were more likely to be to another species ofPedicularis. Although individuals of other genera were in bloom, the bees switched to thePedicularisspecies most synchronous in time and space to the previously preferredPedicularisspecies. Counts were made of the number of pollen grains per flower, the reward for foraging bees. The last species to flower had the greatest reward but also had the largest ratio of the number of pollen grains to the number of ovules as compared with the previously floweringPedicularisspecies. These results suggest that pollinator sharing is an important evolutionary force but that the quantity of the pollen reward may be more related to the number of ovules.