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Plant parts like petals, leaves and stems have little holes called stomata – kind of like the pores in our skin. When stomata open, water escapes. When this happens the water is replaced by the plant absorbing water up from the roots into the stem and leaves and petals. As water evaporates from the leaves and petals more water is sucked up through the stem from the roots. This is called tranpiration…kind of like a person sucking on a straw. What You Need:
- White Flowers (Carnation, Queen Anne’s Lace)
- Food Coloring
Fill a vase with water. Add food coloring to the water. Collect or buy some white flowers. Make a fresh cut at the end of the flower stem and put the flowers in the water. Check on the flowers every hour. How are the petals changing?
- ZOOM Science Rocks: Coloring Flowers 
- Museum of Science and Industry: Color Changing Carnations 
- USGS: Tranpiration 
- Mythbusters Science Fair Book  – Observe Colorful Transformations from Transpiration (Pages 64-65)
- Super Simple Things To Do With Plants : Carnation Caper (pages 20-23)
Words to Know: Cohesion – When molecules of the same substance stick together. Transpiration – The loss of water from the parts of plants; petals, leaves, stems, flowers, etc. Absorb – To soak up. Evaporation – Water changing from a liquid to a vapor.