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Xylem & Phloem

Xylem: -Transports water and soluble materials.

Phloem: -Transports sugars.


  • The vascular bundle is found in the centre.
  • The arrangement provides strength to withstand the pulling forces to which roots are exposed/
  • Around the vascular bundle the cells are called the endodermis - they help to get water into the xylem vessels.
  • Inside the endodermis is the pericycle: contains meristem cells that can divide.
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  • The vascular bundles found near the outer edge of the stem. 
  • Xylem is found towards the inside of each vascular bundle; phloem is found towards the side.
  • In between the xylem and phloem is a layer of cambium.
  • Cambium is a layer of meristem cells that divide to make new xylem and phloem.
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  • A dicotyledon leaf has a branching network of veins that get smaller as they branch away from the midrib.

                                                         Structure of Xylem

  • Consists of tubes for water, fibres for support and living parenchyma.

Xylem Vessels

-Long cells with thick walls containing lignin.

-Lignin waterproofs walls of cells and strengthens them.

-Cells die and end decay, forming a long tube

-Lignin forms spiral, rings or broken rings.

-Some lignification is not complete, and pores are left called pits, allowing water to move between vessels.

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