What is the purpose of the cortex and pith?

Answer 1

The pith of a tree is formed during the first year of growth and becomes a storage area for impurities that are deposited from the active xylem during the growth of the tree. The pith or "heart wood" is more resistant to rot and was used for the base of log cabins before foundations. The center of the tree has also been sought ofter for fence posts due to the resistance to rot.

Answer 2

The pith, whose parenchyma cells like those of the cortex, function in food storage.

Pith

The pith occupies the large central part of the stem. It consists of thin-walled parenchyma cells with intercellular air spaces. Between each vascular bundle is a band of parenchyma, the medullary rays, continuous with the cortex and the pith.

• The cells of the pith store water and starch.
• They allow for the exchange of gases through the intercellular air spaces.
• The medullary rays transport substances from the xylem and phloem to the inner and outer parts of the stem.

Cortex

This region comprises the collenchyma, parenchyma and endodermis. It is situated to the inside of the epidermis.

• Collenchyma

  These cells lie under the epidermis and constitute three to four layers of cells with cell walls thickened at the corners. The collenchyma cells contains chloroplasts

  • Functions of the Collenchyma

  • This tissue serves to strengthen the young stem.
  • The chloroplasts are responsible for the synthesis of organic food during photosynthesis.

• Parenchyma

  Beneath the collenchyma cells are a few layers of thin-walled cells, parenchyma, with intercellular spaces. The parenchyma cells make up the bulk of the cortex.

  • Functions of the Parenchyma

  • The synthesized organic food (mainly starch) is stored here.
  • The intercellular air spaces are responsible for gaseous exchange.

• Endodermis or Starch Sheath

  The endodermis or starch sheath forms the innermost layerof the cortex. This is a single layer of tightly-packed rectangular cells bordering the stele of the stem.

  • Functions of the Endodermis

  • The cells of this tissue store starch.
  • It allows solutions to pass from the vascular bundles to the cortex.