The most obvious features of a young stem are bundles of vascular tissues, held in place by the surrounding pith and cortex. The word vascular is derived from the Latin vasculum, “little vessel,” and refers to the fact that water, minerals, and food molecules are transported through ductlike cells in plants. The inner half of each vascular bundle consists of large, water-conducting cells of xylem tissue; toward the outside are food-conducting phloem cells that are smaller. These vital tissues form pipelines of fluid transport, connecting leaves, stems, and roots.
