Xylem & Phloem Distribution (Cambridge (CIE) AS Biology): Revision Note

Xylem & phloem distribution

Xylem

• The functions of xylem tissue in a plant are:

  • Vascular tissue that carries dissolved minerals and water up the plant

  • Structural support

• Xylem tissue is found, along with phloem tissue and other tissues, in vascular bundles

Phloem

• 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

    • On the edges of the centre core is the phloem tissue

  • In the stems, the vascular bundles are located around the outside

    • 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)