A new apparatus to measure the rate of fall of seeds

1. Seed dispersal is widely recognized to be of crucial importance in the ecology of plant communities, yet characterization of dispersal capacity rarely goes beyond two categories: 'good' and 'poor' dispersers, defined on the basis of dispersule morphology. 2. We describe a new apparatus which determines the rate of fall of seeds in air by detecting their passage through two fans of laser light. 3. This apparatus is able to measure rate of fall in smaller seeds than previously published methods and reveals that there is no justification for the arbitrary division of species into two wind dispersal categories.