The Effect Of Flowering Phenology On Reproduction In Lupinus Perennis

Constance E. Hausman, Helen J. Michaels, and Randall J. Mitchell

Variation in flowering time may influence reproduction through effects on plant-pollinator interactions and/or resource availability. We examined the effect of within-plant variation in flowering time on components of offspring reproduction in Lupinus perennis, a threatened herbaceous perennial of Midwestern oak savannas. We classified all inflorescences on 15 individuals into discrete phenological classes. To prevent seed dispersal, we bagged the inflorescences after senescence of all flowers. Fruit production per flower varied among genets, but was not affected by inflorescence phenology. However, early flowering inflorescences produced significantly fewer seeds per fruit, and had significantly heavier seeds. In a greenhouse experiment seedlings from early inflorescences emerged slightly faster and had more leaflets, while cotyledon leaf area was smaller in seedlings from late inflorescences. These results are consistent with the notion that pollinator limitation may be more important than resources early in the flowering season.