The Optimal Growth of Helianthus Annuus

The history of optimality theory and its application to plant growth is reviewed. The theory is developed for Helianthus Annuus and compared to the actual growth data for this plant, assuming that the objective of the plant is to maximize the amount of its reproductive portion within one growing season. The theory is complicated by the actual logistic form of both the vegetative and reproductive growth phases and by the overlap of these two phases. The fit of theory and data is improved if the plant is further assumed to time discount—to place more emphasis on the success of its seeds produced early than on seeds produced later. This sort of behavior seems especially appropriate when the length of the growing season is uncertain.