Pollination, reproduction, and fire in California Arctostaphylos.

The pollination biology as related to divergent post-fire reestablishment strategies was examined during flowering sequences for two years in sympatric populations of Arctostaphylos pringlei and A. glandulosa var. mollis. Arctostaphylos pringlei reestablishes post-fire populations by means of fire-stimulated germination of previously dormant seeds, while A. glandulosa var. mollis resprouts from large subsurface burls. Arctostaphylos pringlei produced more flowers per unit plant size, exhibited faster nectar production and higher nectar concentration, attracted nearly twice the number of pollinator visitations, and set more seed when self-pollinated. This substantiated the hypothesis that in these two species the amount of reproductive energy allocated to flower, nectar, and seed production reflected the relative significance of "seeding" compared to a "resprouting" post-fire establishment strategy.