Morphogenesis of wavy epidermal pavement cells in plants has fascinated researchers for decades. A mechanical mechanism had been proposed in which the anticlinal cell walls, forming the in-plane cell borders, feature contiguous stiff and soft zones that generate waves upon stretching. We replicated this model as designed and also expanded on it to test its validity for three-dimensional (3D) cell geometry. Our results suggest that both the assumptions going into and the predictions arising from this hypothesis do not stand closer scrutiny and may misguide experimentalists. Unlike what the published data seem to suggest, we observed that only waves of negligible magnitude can be formed by this anticlinal stretch model and that these are virtually eliminated when full 3D geometry of the cell is considered. Further, the model produces cell wall stresses that do not match the experimental evidence. Display omitted •Model of wavy cell morphogenesis based on in-plane tension of anticlinal wall tested in 3D•Stress predicted by the model does not match microtubule or cellulose profiles•The periclinal walls of pavement cells are crucial in cell morphogenesis•Simplifying assumptions in modeling approaches must be carefully validated A mechanical model for plant pavement cell morphogenesis suggested that contiguous stiff and soft zones in the anticlinal walls can produce wavy cell borders upon tension. Bidhendi and Geitmann re-evaluate this model and challenge its function when considering 3D geometry and argue that its predictions are inconsistent with biological data.