Canards at folded nodes

Folded singularities occur generically in singularly perturbed systems of differential equations with two slow variables and one fast variable. The folded singularities can be saddles, nodes or foci. Canards are trajectories that flow from the stable sheet of the slow manifold of these systems to the unstable sheet of their slow manifold. Benoît has given a comprehensive description of the flow near a folded saddle, but the phase portraits near folded nodes have been only partially described. This paper examines these phase portraits, presenting a picture of the flows in the case of a model system with a folded node. We prove that the number of canard solutions in these systems is unbounded.