Why Do Leaf-Peepers and Scientists Love This Time of Year?

Autumn Fall Leaves
This time of year can be spectacular if you live in the Northern Hemisphere. (You’ll have to wait till April/May for your turn if you live in the Southern Hemisphere).  Whilst the temperatures may be starting to fall and daylight hours are shortening, Nature makes up for the gentle slide into Winter with a spectacular display of colour during the Fall.  But where do all these gorgeous leaf colours come from?


Leaves contain the pigment chlorophyll, which is contained within organelle called chloroplast. Leaf structure
They’re abundant during the growing season and responsible for chlorophyll’s green colour. The green that we see in leaves is a dominant pigment and we’re actually unaware that it hides red and yellow hues during the growing season. 

The function of chlorophyll is to capture light from sunshine to turn into food and energy via simple sugars made from water and carbon dioxide (CO2).  These sugars are the source of carbohydrates which promote growth and development in plants and trees resulting in the production of O2 (photosynthesis). This process is kept up all summer long and leaves retain their luscious 'green-ness'.  But as daylight hours shorten, cork cells form at the base of each leaf vein which restrict the flow of fluids and minerals.  This process starts slowly at first but speeds up as daylight becomes less abundant.  Although the chlorophyll decreases some leaf veins can still Autumn Fall Leaves

retain some of their original colour, creating the look of drawn-on green lines. 

There are many thoughts about why leaves turn from green to bright yellow, gold, orange and reds. Some thought it was nature’s way of preventing damage from wind and snowfall but the anthocyanins that create the Fall colours have been proven by scientists not to have anything to do with leaf drop.  



The Smell of Autumn is… Candyfloss!

In some areas it's not just a visual display that Fall creates for the Leaf-Peepers – A tree called the Katsura Tree (Cercidiphyllum japonicum) is a hardy tree often known as the 'Candyfloss Tree 'or 'Toffee Apple Tree' – the fallen decomposing yellow & orange leaves of the Katsura Tree fill the air with strong smell of burnt sugar or sweet candy-floss fragrance!

Here is a quick guide to knowing your trees by the color their leaves turn in the Fall:




Sugar Maple=Orange

Black Maple=Yellow

Red Maple=Brilliant Red

Fascinating Science Facts about Fall: 

  • Aurora Season – NASA says that the number of geomagnetic storms are much more frequent during Fall than at any other time during the year. 
  • People who live on the equator or central area of the Earth never experience Fall/Autumn.  After the sun crosses the earth’s equator, and the earth continues its path around the sun, the days become shorter and the nights become longer. The change is most notable for people who live at higher latitudes. 
  • We prefer to eat carbohydrates during spring and summer but opt for fattier foods during the autumn which leads to seasonal weight gain.  Lack of the sunshine vitamin, Vitamin D, can also lead to weight gain during autumn and winter as the lack of this vitamin reduces fat breakdown and triggers fat storage.
  • Seasonal Affective Disorder (SAD) affects between 4-5% of the worlds population and generally affects more women than men
  • Monarch butterflies migrate from the U.S. to Mexico and some parts of Southern California during the Fall.  These butterflies can fly at speeds ranging between 12 & 25 miles per hour.  This is the only insect that migrates to a warmer climate that is 2,500 miles away!

Try This Leaf Color Experiment At Home:

You can try a simple experiment to help you see the hidden colours in leaves.  

  1. Gather some leaves from outdoors
  2. Take one leaf, tear it into small pieces and place in a plastic cup (one leaf per cup)
  3. Then pour enough nail polish remover to cover the torn up leaf
  4. Use a strip of a coffee filter (make sure you label it with the original colour of the leaf) and stand it up into the nail polish remover in the cup.
  5. Wait 10 minutes and watch the liquid travel up the filter
  6. Take the coffee filter strip out and let it dry
  7. Now you can compare the results for all your leaves.

Leaf Chromatography

Which colours did you extract?

Make sure you explore our full ranges of Botany Experiments & Kits, Dicotyledonous Plant Models, Plant Anatomy Models and Monocotyledonous Plant Models to provide your students with hands-on learning opportunities this Fall.





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