Figure 2.  Three simulations of plant-herbivore interaction in which two plants differ in their susceptibility to (or suitability for) herbivores.  Solid line: no plant growth limitation (equations 9, 10).  Dashed line: plant growth cutoff at s0 (equation 4).  Dotted line: logistic model (equation 5).  The two models with plant growth limitation result in a limit cycle or stable equilibrium, respectively.