Leaves



                                                      

    Leaves are an extraordinary sight during autumn when the colors change, and you can see the bright oranges, yellows, reds, purples, and browns.  But, do you really know why those colors are there, and why it is only some trees?  Do you have other questions?  I am 100% sure that you do.

Why do leaves change color in autumn? 

     When summer ends and autumn begins, days will become shorter.  Then, there won't be enough sunlight or water for the trees to go through photosynthesis.  But what is photosynthesis?  Photosynthesis is the process of how plants make food for itself.  Plants would take water by their roots and a gas called carbon dioxide from the air.  Sunlight would be used to make the stored water and carbon dioxide into oxygen and glucose (sugar).  The glucose is the "food" for energy and growing.  A pigment called chlorophyll also helps the process of photosynthesis.  Chlorophyll makes plants have the green color.  Chlorophyll also allows plants to get energy from light.  When photosynthesis stops, the chlorophyll will fade away, which would bring out the bright, beautiful colors. 





Maple Tree



What kind of trees or leaves change color?

     Leaves change color on many deciduous trees, shrubs, and plants.  Deciduous means their foliage will  fall off during autumn.  Oak and maple trees are two of the many deciduous trees that will lose foliage during autumn. 

Is there a reason why leaves will change color?

Trees in winter

     Leaves will change their color during autumn because the tree itself will have to conserve water or survive better in the winter.  To do that, the leaves will have to change color and then eventually fall off.  That will reduce damage caused by insects during winter.  In addition, the process of changing color and falling off can keep the tree from being damaged or destroyed completely.

What colors do the leaves turn?  Why?

Red & Purple	Trees such as maples will have glucose trapped in the leaf after photosynthesis stops.  When the nights are cool and little sunlight shows, the glucose will turn into a red or purplish color.  That will make the leaf a red or purple color.
Orange	Orange is the color the green chlorophyll turns when it fades. Also there are carotene pigments in the leaf that make it orange.
Yellow	Somewhat like the color orange, when the green chlorophyll fades, the yellow comes out due to xanthophyll pigments.
Brown	Brown is the color the leaf turns when there is waste left inside the leaf from glucose.

Chart made by Mai Vo

How did the colors get into the leaf?

      In fact, the colors were always in the leaves.  It just couldn't be seen. During the summer and spring, there is a lot more chlorophyll in the leaves.  All of the green will cover up the orange and yellow pigments until autumn.  Then the red, purple, and brown will come during autumn when photosynthesis is concluding.  It may be a bit confusing for how the color changes, but it is because of each leaf's process.  (Look back at the chart if you need to.)  

What We See

Wavelengths

When you look at a leaf, it appears to be green unless it is autumn.  Green is the first color that hits our eyes.  As stated previously, chlorophyll works like a dye to turn the leaves green during photosynthesis.  So, what is seen is a leaf being green.  There is also a different reason why we see green leaves, and they are called wavelengths of light.  A wavelength includes the rainbow colors red, orange, yellow, green, blue, and purple.  For example, when we see a green leaf, all of the wavelengths will be absorbed into the leaf, but mostly the blue and red wavelengths.  The green would be reflected and that is what we see - a green leaf!


Thank you for reading through my project.  Please leave a comment about it.

Resources: 

"Deciduous - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 10 Oct. 2010. <http://en.wikipedia.org/wiki/Deciduous

"Autumn Leaves - Fall leaf colors - Why do autumn leaves change color and fall?." Science projects, ideas & topics - science fair projects - easy kids science projects & experiments, science articles. N.p., n.d. Web. 12 Oct. 2010. <http://www.sciencemadesimplehttp://www.coolquiz.com/trivia/explain/docs/leaves.asp

"Leaf - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 12 Oct. 2010. <http://en.wikipedia.org/wiki/Leaf

"Autumn Leaves." Kidzone - Fun Facts for Kids!. N.p., n.d. Web. 13 Oct. 2010. <http://www.kidzone.ws/plants/autumn1

Unknown, Pat. "Star*Dreamer's Thanksgiving." Star*Dreamer's Corner. N.p., n.d. Web. 13 Oct. 2010. http://www.star-dreamer.com/11/.

Horton, Jennifer. "HowStuffWorks "Anthocyanins"." Howstuffworks "Science". N.p., n.d. Web. 11 Oct. 2010. http://science.howstuffworks.com/environmental/life/botany/leaves-turn-red1.htm.

"Blog Improvement Overview: 9 Areas to Improve Your Blogging | Visionary Blogging." Social Media Strategy Help -- Visionary Blogging. N.p., n.d. Web. 21 Oct. 2010. http://visionaryblogging.com/blog-improvement-overview/.

"Chlorophyll - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 21 Oct. 2010. <http://en.wikipedia.org/wiki/Chlorophyll

"BibMe: Fast & Easy Bibliography Maker - MLA, APA, Chicago, Turabian - Free." BibMe: Fast & Easy Bibliography Maker - MLA, APA, Chicago, Turabian - Free. N.p., n.d. Web. 7 Nov. 2010. <http://www.bibme.org/>.

My mom for taking pictures of leaves in/on the way to Wausau

Professor Donna Fernandez, Department of Botany- UW Madison

Mr. Roehl

Mr. Johnson