Understanding the mechanism by which patterned gene activity leads to mechanical deformation ofcells and tissues to create complex forms is a major challenge for developmental biology. Plantsoffer advantages for addressing this problem because their cells do not migrate or rearrange duringmorphogenesis, which simplifies analysis. We synthesize results from experimental analysis andcomputational modeling to show how mechanical interactions between cellulose fibers translate throughwall, cell, and tissue levels to generate complex plant tissue shapes. Genes can modify mechanicalproperties and stresses at each level, though the values and pattern of stresses differ from one levelto the next. The dynamic cellulose network provides elastic resistance to deformation while allowinggrowth through fiber sliding, which enables morphogenesis while maintaining mechanical strength.