Optimal Growth Strategies in Annual Plants: 'Bang-Bang' vs. Mixed Strategies

The study of growth strategies of annual plants has been initiated by Cohen (1971, 1976), who has shown that optimally behaving plants in deterministic environments will adopt 'bang-bang' growth strategies. Cohen has also suggested that plants in stochastic environments will select mixed strategies in which biomass is allocated simultaneously to vegetative and to reproductive growth. This prediction has been repeated unchallenged in the literature (see e.g. Schaffer et al., 1982). Nevertheless, it has been shown that if only individual survival during the growing season is random, plants face a world in which a 'bang-bang' growth plan is optimal (Amir, 1978; Mirmirani & Oster, 1978). This plan is randomly aborted when the individual plant dies.