Autumnal leaves?

Question

Can anyone enlighten me as to how the process of autumnal (fall) colours in leaves originated? One would think that (in evolutionary terms) there couldn't be anything to gain from a stunning display of autumn colours, and that it would be more energy efficient for the trees to simply let their leaves simply shrivel up and drop off as winter approaches. So what's in it for the trees?

Ahh - it seems the answer is within us, not the trees. The colours of the leaves are merely coincidental with the cessation of photosynthesis. It is us humans who find the resulting colours so beautiful.

Answer 1

Actually the color show is just a bonus. The tree withdraws the photosynthetic chemicals from the leaves back into itself, and what is left is everything but green. Easy.

Answer 2

I think that this is just a special bonus that we derive from autumn. The story is true - leaves have all these different colour pigments inside them, and they show through when the chlorophyll decomposes as the leaf dies. However, some have better combinations of colour than others. And the ability to show these other colours may have developed by evolution. Most people know about the broadleaf trees that change colour in the fall (before their leaves fall) - e.g. maples, oaks, etc. (I personally dislike the artificially-created pigment combinations in obnoxiously-reddish cultivars, like some basswoods). Most of these are thought to drop their leaves so that they don't lose whole branches if snow should fall on them during the winter. But other trees that have fine colours in the fall (tamarack is one of my favourites) couldn't really suffer from the snow-on-the-branches effect. They probably drop leaves because their leaves will die in the harsh season which is beginning for them - whether or not it will bring danger of freezing or snow. And, finally, leaves don't last forever in the plant world (except on Welwitschia), and a year or two is the most that one can expect from them.

Answer 3

As days shorten and the nights get cooler (usually in mid-to-late August), a chemical clock kicks in and releases a hormone that slows the sap flow to each leaf. Eventually, the leaf is sealed off from the branch and the green chlorophyll fades away to reveal the different chemical pigments that provide the bright colors (which is why you see all these beautiful leaves with spotted bits of color in them).

It's a common belief that cold and frost cause tree leaves to change color, however, they only serve to shorten the span of the leaf's color.

Best condition for colorful autumn leaves is moisture and lower temperatures, however, the colors of the leaves are mostly based on the length of the day.

Answer 4

What a great shame it would be if the trees were unable to display the most wonderful autumnal colours. The onset of winter would feel a lot closer without these displays.

I do not know the answer to your question, though I do know that you are spelling colours correctly thank goodness; too much Americanisation of a great language I feel.

Answer 5

well i'm thinking that's an original question with deep meaning, but i'd bet my bottom dollar the answer is more to do with plant biology, at which i'm a failure. so i answer as an ignorant student.

plant leaves lose their colour, or at least lose chlorphyl from their veins and cells. 'plant biology' - trees gain much by losing their leaves, as, collectively the total leaves which collect as a mass at the bottom of the trunk form as a seasonal layer over a period of time to form a nutrrient rich rotted soil combined to feed itself or provide a base for other plant life to thrive.

on this point if animal life exists around/ on the tree then it is probable that the seed from the tree will become mobile through the gut of an animal, other, to assure the survival of the tree. all trees differ in this repsect or rely on providing for others. so perhaps give with one hand and taketh from the other.

Answer 6

They DO let their leaves shrivel up and fall... only that some colorants (browns, reds, autumnal colors) are more resilient than chlorophyle (green). So, while the leaf is still attached to the branch (because the tree will NOT spend energy making it fall... he LET'S it fall), then the chlorophyle is destroyed fast, while the other pigments take longer to fade away.

Answer 7

Nutrients that HAD been up IN the tree, are going to live in the roots in the tree, for it's protection during the wwnter months. These nutrients leave the Yellow colored, red colored, orange colored and purple sometimes, in the different trees that rise to the outer laters of the leaves, and then fall off the trees, to give the ground nutrients.

Answer 8

When the season begins to change the sap begins to return to the roots of the tree. To keep the tree alive during the cooler months. As the sap begins to return to the roots, the leaves change color &, then die. But, only hard wood trees loose their leaves in the fall. Soft wood trees do not. I have a masters in Botany.

Answer 9

Most leaves that display an unusual autumnal colour red/yellow/orange......are actually that colour anyway. Their true colour is masked by chlorophyll during the summer months so that they appear green.
Funny old world eh!

Answer 10

The answer is simple. They didn't evolve! God created them in a masterful way to display His beauty and glory. Evolution is a hoax crafted to steal away the very purpose of our existence. Check out this site for a lot of the scientific proof for Creation: http://www.answersingenesis.org