Putting a New Spin on the Flight of Jabillo Seeds*

Our presentation describes the explosive seed dispersal of the Hura crepitans fruit. Through high-speed video analysis of an exploding fruit, we observe that the seeds fly with backspin as opposed to topspin, which was previously assumed. Backspin orients seeds to minimize drag during flight since it is stable against gyroscopic precession, and this consequently increases dispersal distance. The seeds’ range is estimated by using results from the seeds of Ruellia ciliatiflora, which are similarly shaped but approximately 10 times smaller than those of Hura crepitans. We note that the effects of lowering drag on the range are more pronounced at higher speeds. We also see that the effect of launch height on the range of the seeds becomes less consequential at higher launch speeds. Our model - developed using the combination of high-speed video analysis of Hura crepitans seeds and results from seeds of Ruellia ciliatiflora - predicts dispersal distances similar to those in a previous study of Hura crepitans seeds.