You can't hurry "autumn"

       The Supremes had a big Motown hit with "You Can't Hurry Love." I have been singing this song and substituting "autumn" for the word 'love' this October as I have been impatiently waiting for the leaves to change colors. But a stubborn thermometer that keeps showing the temperature at 80 degrees and above has been thwarting my hopes. In fact, Asheville set a record for highest temperature one day last week at 86 degrees. The former record was set in 1956.
       The reason a tree's leaves are green in the summer is because they contain chlorophyll. Chlorophyll takes a lot of a tree's energy to maintain, but is worth the effort in the summer when there is abundant sunlight. The chlorophyll takes the sunlight and converts it into nutrition for the tree. But as the days start to get shorter and there is less sunlight for the cholorophyll to 'harvest' it makes sense for the tree to re-absorb its chlorophyll. 
        In the absence of the green chlorophyll the yellow and orange colors of the leaves can now be seen. The yellow and orange colors have always been there but have been masked by the green of the chlorophyll. 
        Burgundy and red color in the leaves, however, are a different matter. They will only occur with a combination of bright sunlight in the daytime and colder temperatures at night. A warmer autumn, like this one, might yield fall colors of yellow and orange but the burgundy and reds will probably be in short supply.
       The photograph below was taken last week in the Pisgah Forest near Brevard, NC.