Abstract: This study investigates pollinators as possible agents of natural selection in influencing flower size in plants.  A comparative study of bilaterally and radially symmetrical flowers was done to see how much variation for flower size is present in each symmetry class.  Petal length was a common characteristic measured for all flowers.  It was found that petal length varies more in radial than bilateral flowers.  To test whether variation was caused by environmental or genetic agents, a study of vegetative characteristics was completed as well.  Leaf length was measured and coefficient of variation compared between the two symmetry classes.  No significant difference in variation was found.  These data imply that floral variation is influenced by different agents than vegetative variation.   Two experiments were completed to investigate whether flower size effected pollinator visitation.  Geranium maculatum and Kalmia latifolia were the study species; treatments were performed to alter petal length, then pollinator visitation was quantified.  Results show significantly less visitation to flowers with greatly reduced petal length, but not to those with slight petal length reduction.  Because it was found that radially symmetrical flowers vary more than bilaterally symmetrical flowers, and flower size influences pollinator visitation, results indicate that  pollinators act as agents of natural selection to influencing flower size.