Abstract: Hybridization in different systems may have widely different reproduction dynamics. Hybridization may be reciprocal or asymmetrical with gene flow primarily in a single direction. The natural dynamics of crossing is mediated by the action of various isolating mechanisms, including pollinator behavior and biological inhibition. This study examined the dynamics of the Silene caroliniana x Silene virginica hybridization system. Morphological analysis determined that the two parent species and the hybrid can be clearly distinguished based on a series of 17 quantitative floral and vegetative characters. Cross-visitation and effective pollen transfer between the parent species was observed during a series of pollinator behavior arrays. Pollen germination, pollen tube growth, and percentage of ovules which were successfully fertilized were all used to quantify the compatibility of a series of conspecific and hybrid crosses. Hybridization between S. caroliniana and S. virginica was determined to be asymmetrical at the level of ovule fertilization, with gene flow primarily in the direction of S. caroliniana.