Parts of the tree

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Parts of the tree

• Grade 8

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Cross section of the tree trunk
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Parts of the tree

• The tree trunk consist of eight parts .They are
• Sapwood
• Heartwood
• Cambium
• Pith
• Annual rings
• Medullary Ray
• Bark
• Inner Bark

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Label diagram
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1. Sapwood

• Sapwood is the outer part of the tree responsible
  for receiving the water and minerals from the
  roots and conducting them around the tree to the
  leaves as well as for food storage. It is located
  between the heartwood and the cambium.

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Location of the sapwood
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2. Heartwood

• Heartwood is the non-active part of the
  tree-usually darker in colour than sapwood- and
  provides the tree with the rigidity often
  necessary to support the crown. The most durable
  wood for timber is from this part of the tree. It
  is located between the pith and the sapwood.

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Location of the heartwood
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3. Medullary Rays

• A ray consist of a strip of wood cells that allow
  sap to move transversely through the wood and
  provide for storage of surplus food and its
  movement when required . They may appear to
  radiate from the pith to the inner bark ,hence
  the name medullary ray is often used.

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Location of the medullary rays
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4. Inner bark / bast

• The inner bark distributes the food substances
  provided by the leaves through the whole of the
  tree. After one growing season it will become
  inactive as a mean of conducting food it takes
  on a new role as the outer bark. It is located
  between the cambium and the outer bark.

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Location of the inner bark / bast
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5. Bark

• The bark makes up the outer sheath of the whole
  tree. It serves to protect the inner parts of the
  tree from
• Fungal attack , Mechanical abrasion by animals
  and other agents , Extreme temperatures and
  Insect attack.

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Location of the bark
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6. Pith

• The pith is the center of the tree. The pith is
  the result of the trees earliest growth a
  sapling wood immediately surrounding it is
  called juvenile wood, which is not very
  desirable as timber.

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Location of the pith
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7. Cambium

• Cambium is the sleeves of cells located between
  the sapwood and the inner bark which covers the
  whole of the tree-that is its trunk, branches and
  twigs. These cells are responsible for growth of
  the tree both its girthdistance around the
  trunk and height. As the cells formed during the
  growing season they become sub-divided in such a
  way that new cells are added to both the sapwood
  and the inner bark.

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Location of the cambium
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8. Annual rings

• This implies that the rings of wood cells ,which
  appear as bands ,are reproduced each year and by
  counting the number of rings we know how old
  the tree was when it was cut down.

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Location of the Annual Rings
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classwork

• 1. Label the cross section of the tree trunk

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classwork

• 2. Give function of each part identified