FIG. 5. A bifurcation diagram showing grass equilibria as a function of the grazing parameter for the system (17)-(19).If , there are three roots. The lowest branch corresponds to the point W where , which is always a stable equilibrium. The middle branch corresponds to the locus of point S as varies. Those points are unstable equilibria, so they are plotted with a dotted line. The highest branch is the locus of point G as varies. This point is always stable.