Ecology of achene dimorphism in Heterotheca latifolia III. Consequences of varied water availability.

Disc achenes were more successful than ray achenes when a plentiful water supply resulted in a high overall biomass and density at the end of the experiment. The inferior performance of ray achenes is attributed to the combined effects of lower embryo provisioning, lower and germination, and suppression by the early-germinating disc achenes. Ray achenes were more successful than disc achenes when water was scarce and overall biomass and density were low at the end of the experiment. Their superior performance resulted from escaping the water shortage by dormancy.-from Author