Plant tissues in a stem section

A tissue is a group of similar cells doing the same job. In a cross-section of a young dicot stem such as sunflower, the outer epidermis is a single protective layer of cells. Inside it is the cortex, made of loosely packed parenchyma cells that store food. A ring of vascular bundles carries materials: in each bundle, phloem on the outside carries food, xylem on the inside, with its wide empty vessels, carries water and minerals up from the roots, and between them a thin layer of cambium divides to make new xylem and phloem so the stem grows thicker. The soft pith in the centre stores food.