Internal parts of a tree

• Outer bark


  • Helps prevent the inside of the tree from drying out because of evaporation
  • Protects the tree from attack from insects, animals, fungi and extreme weather
• Internal parts of a tree

  • Outer bark
  • Medullary rays
  • Heartwood
  • Sapwood
  • Cambium layer
  • Inner bark/Bast
• Medullary rays


  • Store the tree's extra food
  • Carry the tree's food from the bast (inner bark) into the rest of the tree
• Heartwood


  The darker-coloured wood at the centre of the tree, which is made up of dead tree cells. The best wood from a tree comes from the heartwood.
• Sapwood


  The living part of the tree, usually lighter in colour. Transports water and minerals from the roots up to the leaves.
• Cambium layer


  A layer of cells under the bark where the growth of the tree occurs
• Inner bark/Bast


  • Made up of phloem cells, which carry the tree's food or sap down from the leaves to the rest of the tree
  • Helps replace damaged bark
• Ripping bark off a tree will expose the bast
• Maple syrup is made from the sap of the maple tree
• Pith


  A softer layer at the very centre of the tree that is made up of cells from the sapling that the tree grew from. The pith is usually the first part of the tree to decay.
• Annual growth ring


  Each annual ring represents one year's growth of a tree. As a result of our temperate climate in Ireland, a tree will grow more in spring (earlywood) than in summer (latewood). The more a tree grows in spring, the larger the gap between the rings.
• Softwood trees


  • Tracheids store food and carry water and minerals from the roots up the tree to the leaves
  • Medullary rays are very soft and thin and almost impossible to see with the naked eye
  • Resin ducts store and transport resin
• Hardwood trees


  • Fibres provide hardwood trees with their strength, making up most of the tree
  • Vessels transport water and minerals from the roots to the leaves
  • Medullary rays are usually more visible
• Resin is a sticky, gooey amber-coloured substance that some softwood trees produce to heal damage to cells from insects, animals, etc.