What makes flowers open and close?

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Listing Details

Concepts
turgor pressure; plant structure; plants; capillary action; physiology; water
Time needed
30 minutes
Age
6-8
Setting
Home
Materials Needed
  • Construction paper
  • Scissors
  • Shallow dish
  • Water
  • Pen or pencil
Doing the activity!
  1. Trace and cut out two flower patterns (see patterns below).
  2. Fold each leaf of flower into centre.
  3. Float one flower on top of water and rest the other on the table.
  4. Observe what happens to both flowers.
  5. Try to explain what happened
What's happening?

Plant cells are filled with water. This makes the cells firm and causes the plant to be very rigid (plants wilt when they are deprived of water – the cells collapse causing leaves and stems to droop). The pressure of the water inside the plant cells is called turgor pressure.

Some flowers, like Morning Glories, open and close because of changes in the amount of water inside their cells. This water movement through the petals of flowers and the paper flowers you have made is due to capiallary action.

Plants, like paper, have tubes and tube-like structures through which water can move. As the water enters, the turgor pressure produced causes the paper structure to spread open.

 
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