The exodermis occurs beneath the epidermis. Its cells may have Casparian strips (Casparian strip), but more commonly they appear to have a suberin lamella covered by a cellulose wall. The exodermis contains either one kind of cell or short and long cells. The exodermis may be several layers in thickness. If the epidermis collapses, the exodermis becomes the outermost protective layer in roots that do not shed their cortex.