Do you know that flowers can drink up water and change their own colors into the color of the water they drink?
Flowers and plants drink water through their roots.
In cut flowers, since there are no roots, water travels from the cut directly into the stems and travels to the petals and other parts of the plant.
Three factors contribute to the transportation of water:
- Capillary action Inside the stem, there are tube-like transport tissue, called xylem, that brings water and nutrient to different parts of the plant. Water molecules are attracted to the surface of the xylem cells by weak electrical attractions. This sticky property is called adhesion. Water automatically moves up the xylem due to adhesion and the resulting movement is called capillary action1.
- Cohesion Water molecules are not only attracted to the surface of xylem (adhesion), but they are also attracted to one another. This property is called cohesion. Because of cohesion, water molecules fill the column in the xylem as they move up and act as a continuous stream of water2.
- Transpiration Water evaporates from the plant through transpiration. As water evaporates in the petals or any part of the plant exposed to air, a negative pressure is created in the xylem, resulting in suction pulling the water upward just like you draw water upward when you suck on a straw3.
Through these three properties, color water is transported to the petals and the color shows up in the xylem cells on the petals.
- white/light-colored flowers such as daisies or white roses
- food coloring
- several glasses, vases or test tubes
- adult supervision
- Fill each glass with fresh water from the tap. Put 2-5 drops of food coloring into it, one color each. You can also mix the colors (e.g. blue + yellow = green) to get all the rainbow colors.
- Trim at least half an inch of stem off the flowers before putting each into the glass and each time you change the water.
- Add flower food if it is provided.
- Keep them in a cool place overnight.
- Observe the change in colors in the petals.
- If you use flowers such as daisies that take longer to do this experiment, change the water entirely every 2-3 days to keep the flowers fresh for longer.
- Try this bonus experiment: cut along the stem into two halves and stop before reaching the flower. Insert each half into a different colored water. Observe how the petals change color.
- After a few days, the white flowers will change into the colors the flowers were immersed in.
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Learn More About Water Properties
- 1.Pickard WF. The ascent of sap in plants. Progress in Biophysics and Molecular Biology. 1981:181-229. doi:10.1016/0079-6107(82)90023-2
- 2.Steudle E. THECOHESION-TENSIONMECHANISM AND THEACQUISITION OFWATER BYPLANTROOTS. Annu Rev Plant Physiol Plant Mol Biol. June 2001:847-875. doi:10.1146/annurev.arplant.52.1.847
- 3.Gardner WR, Ehlig CF. The influence of soil water on transpiration by plants. J Geophys Res. October 1963:5719-5724. doi:10.1029/jz068i020p05719