Meeting Abstract

P2.76  Monday, Jan. 5  The mechanics of explosive seed dispersal in Orange jewelweed HAYASHI, M*; FEILICH, KL; ELLERBY, DJ; Wellesley College dellerby@wellesley.edu

Explosive dehiscence aids seed dispersal in a number of plant species. Orange jewelweed (Impatiens capensis, Meerb.) is an herbaceous annual exhibiting this type of dispersal mechanism. High speed video analysis was used to determine the sequence of events during seed release in this species. Longitudinal splitting of the pod into 4 rapidly coiling segments launched the seeds. Splitting and coiling took 4.2 +/- 0.4 ms (mean +/- SEM, N = 8). Stored elastic energy as a result of turgor pressure is the likely driving force behind rapid plant movements. Isolated coils were attached to an ergometer and their stress-strain relationships were determined. Stress increased with coil hydration, confirming the role of turgor pressure. The energy storage capacity of the coils was 124 +/- 37 J/kg (mean +/- SEM, N = 8), similar to that of spring steel. Analysis of the kinetic energy of the launched seeds will determine the effectiveness with which stored elastic energy is transferred to the seeds.