Why exacty do leaves change color in the fall?

Answer 1

Chlorophyll.

Let's put it this way - leaves are green because they make a chemical that absorbs light... chlorophyll. They make so much of it, that its colour ends up predominating over any other colour that might be in the tissues. So leaves are green because they're chock full of chlorophyll, and chlorophyll looks green.

In the autumn, leaf-bearing trees start to shut down. New chlorophyll is made slower than it breaks down, so the green colour fades and you can start to see many of the other pigments that were present in the leaves all along, but just covered up by all the green. These other pigments are called carotenoids (like beta-carotene, which makes carrots orange) and come in lots of different colours: brown, yellow, orange, and basically most of the other colours you associate with autumn leaves.

There are some pigments which are only produced in the fall just as the chlorophylls are starting to be not produced. These anthrocyanins are responsible for reds and purples in leaves. Anthrocyanins in leaves are usually the result of sugar that hasn't been transported properly, so certain environmental conditions can cause much more red than others (sunlight is one, so usually one side of a leaf is much redder than the other side).

Hope that helps! There's a lot more going on in leaves than most people suspect!

Answer 2

Chlorophyll Breaks Down

But in the fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food-making process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible and give the leaves part of their fall splendor.

At the same time other chemical changes may occur, which form additional colors through the development of red anthocyanin pigments. Some mixtures give rise to the reddish and purplish fall colors of trees such as dogwoods and sumacs, while others give the sugar maple its brilliant orange.

The autumn foliage of some trees show only yellow colors. Others, like many oaks, display mostly browns. All these colors are due to the mixing of varying amounts of the chlorophyll residue and other pigments in the leaf during the fall season.......

Answer 3

All the reasons given above are not appropriate. During leaf fall, the leaves become yellow in colour or might change to other colours. This is due to the fact that the chlorophyll stored in the leaves is broken down.A chemical called phytochrome triggers plants to go into the dormant period. The pigment left in the leaf is leucoplasts which are for storage of food and degenerate after some time when the leaf completely detached from the main plant and falls to the ground

Answer 4

A tree's roots, branches and twigs can endure freezing temperatures, but most leaves are not so tough. On a broadleaf tree -- say a maple or a birch -- the tender thin leaves, made up of cells filled with water sap, will freeze in winter. Any plant tissue unable to live through the winter must be sealed off and shed to ensure the tree's survival.

As sunlight decreases in autumn, the veins that carry sap into and out of a leaf gradually close. A layer of cells, called the separation layer, forms at the base of the leaf stem. When this layer is complete, the leaf is separated from the tissue that connected it to the branch, and it falls. Oak leaves are the exception. The separation layer never fully detaches the dead oak leaves, and they remain on the tree through winter.

Answer 5

The tree slows down to become dormant in preparation for the cold weather. The leaves more-or-less die because of lack of circulation, like an appendage that has no blood flow.

As the leaf dies, the chlorophyll and other pigments change color as they break down or decay.

Answer 6

Fall is my Fav Debs...The cool air and the leaves are changing too here I certainly have a tree I watch each and all of the time Spring whilst it starts off to Bloom and Fall whilst it starts off to tutor colours!! isn't it merely so tremendously whilst taking a journey ion the Mountains? I certainly have a component for the Blue Ridge Mountains my self and we can Mississippi and finding out on up a chum using fact he has no longer been to the Mountains yet and it extremely is one place i choose for to take him!! We stay at a pals cabin and it extremely is fairly tremendously this time of year did no longer you pick for me to p.c.. up a patch for you next time I went digital message me tell me what you pick for i visit confirm you get it out to you!!!

Answer 7

Not only the chlorophyll, temperature is also a minor causing factor for colour change of the leaves

Answer 8

The colors are always present, however once the weather starts changing and there's less sunlight the leaves slow down their systems hence the green colors fade away

Answer 9

As the outside temperature cools, a leaf's life comes closer to it's end. Chlorophyll is no longer being produced. Eventually, the leaf dies & falls to the ground. In the Spring, a new cycle of a leaf's life will begin to sprout.

Answer 10

I was told once when i was a kid that the colors of the trees are thier true colors.. then all that scientific mumbo jumbo that they all said.. but they colors you see are the trees true colors it just take a little of the cold air i guess for em to come out.. I mean think about it dont you turn different colors when you get cold too?..lol like green (snot) and red(noses) and rose(cheeks)....lol you get the jist though.