: The cells of epidermis, cork and bark are thickened. Bark and cork cells may be dead. They are mainly protective in functions. Prosenchyma, collenchyma and sclerenchyma are simple tissues. Prosenchyma is supporting and conducting tissue where as collenchyma and sclerenchyma are strengthening and supporting tissues. Xylem and phloem are complex tissues in which xylem is water and mineral conducting tissue while phloem is food transporting tissue. Cambium is the lateral meristem responsible for increase in girth of stem and roots.