How Leaves Cha-Cha-Cha-Change Colors For Autumn

Autumn is when every tree is in bloom ~ Ilex Farrell

leavesTo be able to explain why tree leaves change their color in the fall, you must understand the basic physiology of the leaf itself.

Leaves are green because of chlorophylls that function by capturing the sun’s energy and to manufacture food for the plant or photosynthesis. All of this takes place in the plastids (specialized cells). During the growing season, the green color of these chlorophylls masks out all the other colors that may be present. So all you see is green.

As the growing season slows in autumn, chlorophyll production slows and the green-color dominance lowers to reveal the other colors of the leaf. Many influences such as amount of water, sunlight, temperature, and microclimate can manipulate the timing of the color changes.  A couple of weeks of bright sunny days mixed with clear, cool nights seem to bring out the best fall colors.

There are two pigments responsible for fall color:

Carotenoids – provide the yellow, orange, and brown colors.
This one provides the coloring for carrots, corn, and daffodils. Just like chlorophyll, these carotenoids are found in the plastids of the leaf. Some trees that turn hues of yellow or orange are: hickory, beech, black maple, aspen, and birch.

Anthocyanins – responsible for the red and purple hues.
This pigment develops in late summer in the sap of the cells of the leaf. They are created by a response to bright light and too much plant sugars left in leaf cells. Anthocyanins also tint young leaves in spring and allow for the bright colors of red apples, blueberries, cherries, and strawberries. Trees that tend to be colored red to purple are: oaks, dogwoods, red maple, sourwood, and black tupelo.

Both pigments can vary due to many degrees in a leaf, along with outside influences, that cause color ranges that are endless.

21 thoughts on “How Leaves Cha-Cha-Cha-Change Colors For Autumn

  1. I find it almost disconcerting that I am so blissfully happy during nature’s wretched stage of death. Kinda creepy, right? Still, all those colors. sigh
    I can’t even see a scrap of driveway beneath the bazillions of leaves that cover it. It’s truly a yellow brick road.
    I hope you’re having a riotous color extravaganza in the Midwest. Things here in the Mid Atlantic are reaching quite heavenly proportions.

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  2. Thanks for the science lesson. It makes it even more interesting to watch the leaves change. And I guess it means that some trees have subtle differences each year and in different soil types.That was a question I think.

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    • Yes, aside from the actual chemicals that make color, there are different influences that cause different colors: amount of minerals and water available to plant and fall temperatures. If it gets too cold too fast, color tends to suffer.

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  3. Well done and very well understood (even as I knew it before ;)). This year I’ve been impressed with the vibrance of the trees around me. The yellows, golds, oranges, have been really stunning; as it is I have a couple of Hickorys in my yard, bright yellow!

    You know another good one to look out for: a stand of Sumac. I’ll share some pics on my blog soon that I took of a stand of Staghorn Sumacs. They look like parrot feathers, lots of colors, very nice.

    Thanks for this! It’s amazing how nature works. It’s truly magic to see this change.

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