Except for bryophytes,land plants have true roots, stems, and leaves, which are defined by the presence of vascular tissues. The two types of tissues that conduct materials in the plant's vascular system are xylem and phloem. Tube-shaped cells in the xylem carry water and minerals up from roots. These water conducting cells are actually dead, with only their walls remaining to provide a system of microscopic water pipes. Phloem is a living tissue with nutrient-conducting cells arranged into tubes that distribute sugar, amino acids, and other organic products throughout the plant.