Xylem

• The functions of?xylem?tissue in a plant are:
  • Vascular tissue that carries?dissolved minerals?and?water?up?the plant
  • Structural support
  • Food storage
• Xylem tissue is found, along with phloem tissue and other tissues, in?vascular bundles
• The location of the vascular bundles is dependent on which organ they are in as the different organs are under different stresses:
  • In the?roots?the vascular bundle is found in the centre and the?centre core?of this is?xylem tissue. This helps the roots withstand the pulling strains they are subjected to as the plant transports water upwards and grows
  • In the?stems?the vascular bundles are located around the outside and the?xylem tissue?is found on the?inside?(closest to the centre of the stem) to help support the plant
  • In the?leaves?the vascular bundles form the midrib and veins and therefore spread from the centre of the leaf in a parallel line. The?xylem tissue?is found on the?upper side?of the bundles (closest to the upper epidermis)

Phloem

• The function of?phloem?tissue in a plant is to:
  • Transport?organic compounds, particularly sucrose, from the source (eg. leaf) to the sink (eg. roots). The transport of these compounds can occur?up?and?down?the plant
• Phloem is a complex tissue also made up of various cell types; its bulk is made up of?sieve tube elements?which are the main conducting cells and the?companion cells
• Other cell types of phloem tissue also include parenchyma for storage and strengthening fibres
• The location of the?vascular bundles?is dependent on which organ they are in as the different organs are under different stresses:
  • In the?roots?the vascular bundle is found in the centre and?on the edges of the?centre core is the?phloem tissue
  • In the?stems, the vascular bundles are located around the outside and the?phloem tissue?is found on the?outside?(closest to the epidermis)
  • In the?leaves, the vascular bundles form the midrib and veins and therefore spread from the centre of the leaf in a parallel line. The?phloem tissue?is found on the?lower side?of the bundles (closest to the lower epidermis)

The distribution of xylem and phloem tissue in the roots, stem and leaves in a herbaceous dicotyledonous plant