Sclerification

Sclerification 

the thickening and lignification of the walls of plant cells and the subsequent dying off of the protoplasts. Sclerification increases the solidity of the plant’s organs, as well as their resistance to disease agents. Parenchyma cells are most often subjected to sclerification and turned into sclereids; however, epidermal cells are often sclerified as well. The interfascicular parenchyma in palm and bamboo stems is especially susceptible to sclerification. In woody plants sclerification occurs in the outer layers of the bark, affecting the cells of the phloem and radial parenchyma.