Variability in Dispersal Ability of Common Milkweed, Asclepias syriaca, Seeds

Common milkweed, Asclepias syriaca L., produces plumed seeds adapted for wind dispersal. Seeds within single pods are variable in coma length (plume length) and seed mass. Coma length variability is related to a seed's location within a pod, while seed mass is not related to seed position. Laboratory studies, using methods developed by Sheldon and Burrows, revealed that seed trait variation can influence variation in a plant's dispersal profile. Field studies indicated that ambient wind speed as well as seed morphological attributes influenced seed dispersal distance. In strong winds, seeds with relatively long comae travelled significantly farther than those with short comae when paired and released simultaneously. Both laboratory and field results suggest that coma length variation is more strongly related to variation in seed dispersal than is seed mass. The pattern of variability of morphological attributes of seeds within pods may lead to increased chances of seeds reaching sporadically opening patches.