Nature's Color Palette

During the spring and summer the deep green color of chlorophyll assists plants in the absorption of sunlight and masks additional colors lurking in the leaves of trees. The fall colors are there but hidden.  

The green pigment of chlorophyll is produced by plants during the photosynthesis process.  Those other ‘hidden pigments’ are called carotenoids and they are the source of the yellows, oranges, and anthocyanins, which yield red and purple leaves. While chlorophyll and carotenoids are present throughout the growing season, most anthocyanins are produced exclusively in late summer and early autumn.

There are several reasons why leaves change color in the fall, the most significant of which is shorter daylight hours and longer nighttime hours. As the days become shorter and the nights become longer, the amount of light required for photosynthesis is diminished and the production of chlorophyll slows to a halt. Without any new chlorophyll being produced, the leaves' characteristic green color begins to break down and vanish. This mechanism essentially reveals the colors of the carotenoids and anthocyanins that were lurking beneath. 

The red color is actively made in leaves by bright light and cold. The crisp, cold nights in the fall combine with bright, sunny days to spur production of red in leaves – especially in sugar maple and red maple trees. During these days, lots of sugars are produced in the leaf but the cool nights and the gradual closing of veins going into the leaf prevent these sugars from moving out. These conditions — lots of sugar and lots of light — spur production of the brilliant pigments, which tint reds, purples and crimson. 

 

Elevation and variety of tree species are two other factors that affect the timing of fall foliage. Trees in higher mountain elevations are likely to change colors more quickly than their valley counterparts within the same latitude.

We’re lucky here in the Midwest to be blessed with pretty decent fall colors.  They’re slightly late this year - yet continue to delight.

*Photos sourced from the Brussels community and our yard...