What are simple permanent tissues?

Simple permanent tissues consist of cells which are alike in structure and function, working together to perform specific tasks. These tissues are commonly found in the organs, and the outer protective layer (epidermis). These tissues also form the framework of a plant’s structure. Three types of cells constitute the simple permanent tissues: parenchyma, sclerenchyma, and collenchyma. 

1. Parenchyma are viable cells which have thin walls. They are typically oval in shape and have a large vacuole and cytoplasm. This type of cell is found in the pith and cortex of plants, giving structural support and assisting in food storage. 
2. Sclerenchyma cells are dead and have thick cell walls containing lignin. They vary in shapes and sizes and are found in leaf veins, around vascular bundles, and seed coverings. Their primary role is to give the plant rigidity and support. 
3. Collenchyma cells are viable and have elongated shapes with thickened corners in their cell walls. They are found in leaf stalks, and underneath the epidermis; its primary function is giving flexibility and structural support to plants. These cells also have no intracellular spaces.