Are you are lucky enough to live in a climate where the foliage (plant leaves) changes colors with the seasons?
I hope so! If you don’t, I would highly recommend finding the nearest scenic drive and taking a tour. Go peek at the 2018 Peak Fall Colors Map to see when and where the best places may be! In the upper midwest of the United States, we are currently being blessed with a stunning art show put on by the one and only — the natural environment.
Our plant brethren are by no means showing off for our benefit, but we sure like to think so. If not for us, then why does this happen every year?
Because SCIENCE is so neat. And these trees are preparing to go dormant or at least slow down production for the colder months in the northern hemisphere. A short digression on global awareness: fall happens at opposite times depending if you live in the northern or southern hemisphere of our planet. Right now in South Africa? Spring. Yep! And when it start to warm up after the winter in North America or Eurasia, it is beginning to get cold in the south. This is because the earth is tipped slightly on its axis and can be explained in this article here by National Geographic. I’m going to leave that one to the experts.
Wherever you live, the plants around you know that the fall season is approaching when the hours of sunlight are shorter and the air becomes more cool. This triggers a chemical response in the cells of tree leaves.
If you look closely, you will see that different species of trees take claim to different color schemes. If you are looking to learn general categories of trees and where they grow, fall may be a very helpful time.
For example, you are most likely looking at the apen, ash, beech, and birch tree varieties if you see bright yellow leaves. If you are seeing orange tones you might be looking at red maple, sugar maple, or sumac. The reds of fall are typically dogwood, red maple, and oaks.
I’d love to tell you it is that cut and dry, but that would be too simple. There is plenty of color overlap that happens between tree varieties. A perfect example of this is the sugar maple, the kaleidoscope of trees, will display a wide array of different colors even on one single leave!
During the warm and bright months, trees are using a special molecule in their leaves called chlorophyll to absorb sunlight and turn it into usable energy for the leaf cells so that they can produce sugars (food) to send out for the whole tree! Chlorophyll is a pigment and responsible for making plants appear green to our eyes.
However, as the sunlight becomes less prevalent in fall, the chlorophyll molecules begins to break down or ‘die off’. The green color disappears, so what takes its place?
Leaves that become yellow are given a chance to highlight chemical compounds that are present in small amounts year round called carotenoids (yes, just like the color that makes carrots orange!). Carotenoids are present in much smaller concentrations than chlorophyll so they do not display their color until the latter has been broken down. The yellow and orange hues slowly take over the leaf.
The leaves that turn to darker shades of red, purple, or brown are experiencing a different chemical process. In order to turn red, trees need to actively produce a pigment specifically for autumn called anthocyanin. Some of the anthocyanin (which becomes a brownish hue) is made from sugars that did not get sent out of the leaf in time when the plant was shutting down for the season.
Researchers also discovered that the anthocyanin pigments act as a type of sunscreen for the leaves as they try and finalize some food production and transportation late in the season. An additional benefit of the red pigmentation is its ability to ward of pests. A deep, dark red color means that the plant is very healthy. Insects are deterred, knowing they will be better off laying their eggs in weaker host plants with duller colors.
Here is some further reading if you are interested in this topic!
I wish you all the best of times observing these beautiful colors. If you are anything like me, understanding the science behinds nature’s beauty only enhances the experience. Enjoy your new perspective!
xoxo Drifted Way
