Effects of Seed Number and Fruit and Seed Packaging on Dispersal Potential of the Multiseeded Fruits of Eastern Redbud (Cercis canadensis)

Premise of research. Seed dispersal has an essential role in structuring plant populations. Most studies of effects of variation of wind-dispersed diaspore characteristics on dispersal capacity have focused on single-seeded fruits. However, effects of seed number on dispersal capacity of multiseeded fruit diaspores have rarely been explored. We assessed the relationships between seed number and fruit and seed packaging characteristics in multiseeded fruits of Cercis canadensis and how these influence their dispersal potential. Methodology. We performed indoor dispersal experiments with fruits in still air to determine how variability in seed number and mass affected their rates of descent and dispersal distances. Pivotal results. Few-seeded fruits had an asymmetrical distribution of seeds, with more seeds being situated at the bases than at the tips of fruits, whereas seeds were more evenly distributed in many-seeded fruits. Few-seeded fruits had significantly higher rates of descent and dispersed significantly shorter distances compared with many-seeded fruits, despite the former having lower wing loading values. We determined that redbud fruits could be grouped into two aerodynamic types, with few-seeded fruits behaving as rolling autogyros with tight helical trajectories and many-seeded fruits behaving as rolling autogyros with broad helical flight paths. Conclusions. Our findings suggest that differences in seed number and internal seed weight distribution within redbud fruits have variable effects on diaspore flight behavior. Future studies of wind dispersal of multiseeded diaspores will need to account for within-fruit variation in the locations, sizes, and numbers of seeds.