The Science of Autumn Colours

I’ve been watching the trees change colour over recent weeks. They are probably at their best around now. I always hope they’ll stay around for a long time, but invariably we get gales and the trees go bare overnight. Some of them that are growing in exposed spots have already lost almost all their leaves.

Others are still green.

Of those that have changed, I love the range of colours, from the buttery yellow of this willow…

…to the deep orange-red of this ornamental rowan (complete with bright yellow berries).

Some of the Acer (maple) family are the stars of autumn. This one positively glows!

Have you ever considered the science of this spectacle? The leaves are key to everything the tree does. In spring and summer, they are full of the green pigment, chlorophyll. This enables the tree to use energy from sunlight to convert the carbon in carbon dioxide to sugars (by the process of photosynthesis) The sugars fuel growth, flowering and seed production: everything else the tree does. Like a factory needs down time for maintenance and replacement of worn out parts, the tree’s leaves reach the end of their life in autumn. It is the breakdown of the green chlorophyll pigment that gives rise to the yellows, oranges and reds of autumn leaves.

Shorter day length stimulates the tree to produce a layer of weak cells at her base of each leaf stalk. This is called the abscission layer and causes the leaves to detach easily and fall.

The trees will now remain dormant during winter until fresh green leaves emerge in spring, ready to go into full production. Nature is pretty amazing!.

Having been out and about looking for autumn leaf colour, I forgot this in our own garden. It’s a little Japanese maple we’ve had for years that always looks stunning at this time of year.

How are the trees looking where you are?

Author:

I live in Northumberland, within sight of the sea and spend my time knitting, crocheting, sewing and trying my hand at different crafts. There's usually a story to share about the things I make.

4 thoughts on “The Science of Autumn Colours

  1. Your Japanese maple is beautiful. We used to have one. Sadly bugs got into the trunk and we didn’t notice in time.
    We have a full range outside. There are everything from nearly bare trees to nearly full green. We usually get a fall wind storm in October that takes most of the leaves down. It hasn’t happened yet.

    Liked by 1 person

  2. Such stunning acers this time of year. I have particularly noticed near me the colours this year seem more vibrant that usual. A friend suggested it was the extra hot weather this summer that made the leaves brighter and more noticeable as they fall. Not sure if that’s true but if so then that’s a pretty way to think of autumn.

    Liked by 1 person

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