What Do All Trees Have in Common?

1. The crown, or the leaves and branches at the top of a tree, filters dust from the air. It provides shade and helps raindrops fall softly to the ground.
2. The leaves and needles make food for a tree. Remember what you learned about photosynthesis? Chlorophyll gives leaves their green color. Leaves use the sun’s energy to transform carbon dioxide and water into sugar and oxygen. The sugar is the tree’s food. It is either used or stored in the branches, trunk and roots. The oxygen is released into the atmosphere for us to breathe.
3. Flowers and cones produce seeds which the tree needs to reproduce itself. Seeds contain almost everything a plant needs for life. Seeds are covered with a seed coat that protects it from drought. When the seed is given water, it expands and loses its seed coat. The seed begins to grow or germinate growing both roots and a stem.
4. A tree’s roots absorb water and nutrients from the soil, anchor the tree in the ground, and store sugar. The larger the tree, usually, the farther its roots grow.
5. The trunk or stem supports the tree and transports food and water.  Knots show where branches used to be.  The trunk has many different layers. 
   



The Parts of the Trunk

• Bark protects the trees from insects and disease. 
  
• The pith is the centre of the tree
• Heartwood is older wood that is darker in colour. 
  
• The xylem or sapwood at the centre of the tree is young wood. The xylem has tubes that allow nutrients and water from the roots to flow up to the rest of the tree. As xylem dies, it becomes heartwood.
  
• The cambium is a very thin layer of growing tissue that produces new cells that become either xylem, phloem or more cambium. Every growing season, a tree’s cambium adds a new layer of xylem to its trunk, producing a growth ring. 
  
• Phloem or inner bark contains food or sap (sugar and nutrients dissolved in water) that travel from the leaves downward..
  

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