Autumn is the season of colours

Colours are all around us. And should we stop for long enough to notice them, we realise they make our world not just look incredible, but our experiences a whole lot richer. They are, after all, what enables us to become awestruck at such scenes as a sunset, a rainbow lorikeet, a Henry Matisse or Van Gogh painting, and the bloom of the cherry blossoms in spring.

But beyond mere pleasure for the senses, in the natural environment, colours have a whole other world of meaning beneath the surface. And we are now well and truly in Autumn (more like winter), what better way to explore this notion than by taking a closer look at trees and their ever-changing leaves.

The colour of leaves come from various pigments. These pigments are natural substances produced by the tree to help it obtain food — in the process, we know from school science class as photosynthesis. The pigments include chlorophyll (green), carotenes (yellow) and anthocyanins (reds and pinks).

Every single leaf on a tree is like its own mini canvas. With the depth and range of colour, they have been influenced by a mixture of weather conditions, location on the tree, and which pigments or chemicals are currently being recruited to work.

In the Autumn, for just a few weeks, we see leaves of deciduous trees and shrubs turn an array of colours from yellow, golden, and orange, to pink, purple and russet. Trees are preparing to lose their leaves to conserve water and better survive through the winter. Without their leaves, they can preserve moisture in the branches and trunk and avoid drying out and dying.

It’s as a seeming byproduct of performing this act of survival that trees just so happen to offer us a brief and spectacular feast for our eyes.

At a chemical level, what’s happening here is that trees are slowing down the production of the chlorophyll that obtains energy from sunlight, allowing yellow and orange carotenes that are normally masked by the green to become visible.

A layer of cells then forms across the base of the leaf stalk, restricting the flow of sugars back to the tree and concentrating them to form anthocyanins. These lovely rich reds and pinks are not on display every year, but if we’re lucky, and we have cold autumn nights and bright sunny days, we may get to admire such brilliant bursts of crimson and ruby. There is no sight quite like anthocyanins, and maybe part of the reason why we find it them powerful and poets have written about this time for ages is because they mark a time of significant change. Such colours appear right before the leaves break off from the tree and make their descent.

Fall, leaves, fall; die, flowers, away; Lengthen night and shorten day; Every leaf speaks bliss to me Fluttering from the autumn tree. I shall smile when wreaths of snow Blossom where the rose should grow; I shall sing when night’s decay Ushers in a drearier day. — Emily Brontë

So next time you’re somewhere where you can really admire the changing colours of the leaves, rather than just passing by and seeing it as sign of just another autumn, stop for a moment. Notice the vast range of colours, and marvel at such an act of creation and trees for being the prolific and underappreciated artists they are. You might just be so inspired as to make a change yourself.