TURNING OVER A NEW LEAF

It’s fall ya’ll and the leaves they are a changing in the Ozarks.  One of the first to change is sumac followed by poison ivy (BOO HISS – I have poison ivy issues) which turns a lovely shade of red.  So, what causes the color change in leaves this time of year?  Thanks for asking!  Leaves naturally have many pigments in their cells.  The green color we see in leaves is from the pigment chlorophyll that is hugely important in photosynthesis.  Orange and yellow colors are thanks to carotenoids.  Carotenoids also help with photosynthesis and protecting the leaves (a bit like sunscreen).  Lastly, anthocyanins produce the red color.  They too are used in photosynthesis.  Each of these different pigments absorb different wavelengths of light for use in photosynthesis.  The colors they don’t absorb are reflected to us as the color we see. 

Okay, we must now diverge into the physics of light.  Bear with me.  It won’t hurt.  Light functions as a particle and as a wave.  When we see a rainbow, or see the spectrum of colors through a prism, we are seeing the different wavelengths of light separated out.  These appear to us as colors.  When we recognize a leaf as green, that leaf is absorbing all other colors of the rainbow EXCEPT green.  The green wavelength is what is left over to bounce to our eyes.  (The selected soundtrack song for this is “Roy G. Biv” by They Might be Giants.)

Back to fall.  When our amount of daylight becomes shorter and temperatures begin to cool most plants start to become dormant and will quit producing new chlorophyll.  As that chlorophyll declines, the other colors that have always been there, become visible.  We see recognize the “fall colors” of red, gold, and orange.  Those plants that keep their chlorophyll all year (e.g. holly, pine trees, cedar trees…) are called “evergreens” because… they are ever green.

So, here is a fun way to spend some time and prove I’m not making this up to make you sound like a dork.  Get some spinach.  Blend it up.  Put it into a glass.  Mix in some acetone (a.k.a. fingernail polish remover – the REAL stuff).  Add a strip of coffee filter (other paper works, too in a pinch) so that some of the coffee filter is in the goo and the other is sticking out of the goo.  Then wait.  Over the next 24 hours the spinach cells that you macerated will leak out their pigments.  These pigments will be drawn by capillary action up the filter paper.  Big particles will not travel as far up the filter paper as small particles.  As a result, you will have bands of different plant pigments!  Walla!  You have successfully completed a scientific demonstration and you are brilliant.  Go buy a lab coat.