Despite the fact that about seventy percent of all flowering plants are hermaphroditic, the reproductive consequences of combining both sexes on a single plant are still poorly understood. Traditional studies of reproductive success in such plants have focused on fecundity, ignoring the affects of pollen flow. Recent investigations have switched attention to patterns of paternal gene flow in search for "sexual selection" in plants. Few studies to date have attempted to quantify the affects of floral characteristics on both male and female reproductive fitness. I propose to investigate the affects of inflorescence size on the reproductive success of Yucca whipplei, a semelparous hermaphrodite native to southern California. Inflorescence size typically differs greatly between males and females in dioecious plant species, indicating that selective pressures on inflorescence size are not the same for the two functions. Several alternate hypotheses which could explain apparent overproduction of flowers by Yucca whipplei will be tested. These hypothesis include aspects of both male and female reproductive success. This research will help determine some of the fitness consequences of hermaphroditic reproduction, and how plants can respond to the sometimes conflicting selective pressures resulting from combining both sexes on a single individual.
