# What causes leaves to change color?

**URL:** <https://boards.straightdope.com/t/what-causes-leaves-to-change-color/136198>\
**Category:** Factual Questions\
**Created:** [November 11, 2002, 12:10am UTC](https://boards.straightdope.com/t/what-causes-leaves-to-change-color/136198 "2002-11-11T00:10:25Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![regnad\_kcin](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@regnad\_kcin](https://boards.straightdope.com/u/regnad_kcin)\
**Post date:** [November 11, 2002, 12:10am UTC](https://boards.straightdope.com/t/what-causes-leaves-to-change-color/136198/1 "2002-11-11T00:10:25Z")

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Ive searched the archives high and low, but no sign of this one being answered by Mr. Adams. He must have answered it, considering what an obvious question it is, but perhaps someone here can help out:

What causes leaves to change color in autumn?

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**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\
**Post date:** [November 11, 2002, 12:22am UTC](https://boards.straightdope.com/t/what-causes-leaves-to-change-color/136198/2 "2002-11-11T00:22:47Z")

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See [http://www.na.fs.fed.us/spfo/pubs/misc/leaves/leaves.htm](http://www.na.fs.fed.us/spfo/pubs/misc/leaves/leaves.htm)

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**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\
**Post date:** [November 11, 2002, 1:26am UTC](https://boards.straightdope.com/t/what-causes-leaves-to-change-color/136198/3 "2002-11-11T01:26:05Z")

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> [@](#):
>
> Both chlorophyll and carotenoids are present in the chloroplasts of leaf cells throughout the growing season. Most anthocyanins are produced in the autumn, in response to bright light and excess plant sugars within leaf cells.
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> During the growing season, chlorophyll is continually being produced and broken down and leaves appear green. As night length increases in the autumn, chlorophyll production slows down and then stops and eventually all the chlorophyll is destroyed. The carotenoids and anthocyanins that are present in the leaf are then unmasked and show their colors.

But, as noted in the first paragraph, the anthocyanins are not present in the leaf until the autumn, after chlorphyll production ceases. So the reds in the maples and other bright colors of some trees were not there underlying the chlorphyll, but produced after production of chlorphyll has stopped. BTW, this was discussed by Adams (but described incorrectly) and also in a prior thread in this forum.

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**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\
**Post date:** [November 11, 2002, 3:57am UTC](https://boards.straightdope.com/t/what-causes-leaves-to-change-color/136198/4 "2002-11-11T03:57:35Z")

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It is also important to note that the reduction in hours of daylight as well as temp triggers the reduction in sap production. This, in turn, cuts down on the production of chlorophyl which allows other color-producing agents, such as xanthophyl to dominate bringing out yellow hues, for example. (As best as I recall from my past advanced biology knowledge). - Jinx