what determins the color?

Question

of fall leaves,, take maple trees,,, one turns red, and another turns yellow, and yet another tree, turns orange?
I'm just curious is all.
thanks for any and all input.

Answer 1

During winter, there is not enough light or water for photosynthesis. The trees will rest, and live off the food they stored during the summer. They begin to shut down their food-making factories. The green chlorophyll disappears from the leaves. As the bright green fades away, we begin to see yellow and orange colors. Small amounts of these colors have been in the leaves all along. We just can't see them in the summer, because they are covered up by the green chlorophyll.

The bright reds and purples we see in leaves are made mostly in the fall. In some trees, like maples, glucose is trapped in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn cause the leaves turn this glucose into a red color. The brown color of trees like oaks is made from wastes left in the leaves.

Answer 2

There are molecules that can absorb light from the sun. They absorb only a small portion of the spectra reflecting the rest. We see what they do not absorb as the leaf color. What they absorb is the start of photosynthesis or other functions. These molecules, called pigments, come in three types or classes of pigments in the leaves of plants: chlorophylls, carotenoids, and anthocyanins. Each absorbs and reflects in a different way so we see them as different colors.
Chlorophyll is the most common but the carotenoids are present in smaller amounts. That is why there are so many variations in green leaves with some being yellower and some being bluer, the ratio of each of the two pigment classes varies with the kind of plant.
In fall it gets colder, days shorten and the chlorophyll breaks down and is not replaced. The carotenoids remain functioning longer or are produced in larger amounts so are revealed. The yellow-green leaf becomes just yellow before dying.
The red leaf begins producing anthocyanins in the fall as it stops the chlorophyll. [Some plants also produce these briefly, in spring, on new leaves before the chlorophyll]
Leaves with good amounts of both anthocyanins and carotenoids will appear very orange.
Anthocyanins produce red, blue, purple, or magenta colors. Recent literature reports some 550 anthocyanins.
Carotenoids produce yellow, orange, or red There are over 600 known carotenoids.
Chlorophylls produce green and have only a few forms.

Why do the leaves change color as opposed to how they do it. In case you wish to go a little further there is a theory that the brighter red colors of fall act as a signal to the herbivorous insects, like aphids, that eat the trees. The plant is saying do not eat me I have defenses. The strong red color in tree leaves associates with the production of another toxic molecule in these trees. This is just like a bright red insect that is poisonous warning off possible predators.
There are other theories.

http://en.wikipedia.org/wiki/Signalling_theory
http://en.wikipedia.org/wiki/Color_change_in_leaves
http://72.14.253.104/search?q=cache:36WZnCfF85oJ:harvardforest.fas.harvard.edu/research/leaves/pdf/Schaefer_and_Wilkinson_TREE_2004.pdf+red+leaf+insect+coevolution&hl=en&ct=clnk&cd=1&gl=us&client=firefox-a