Well, after rain the night before last, and a cold wind blowing in last night, it was 67 F this morning! And delightful all day. Interestingly, there seems to have been another hatch of Green June Beetles this morning. There are everywhere about this afternoon, and two or three of them were still in the lawn as I was mowing it. I believe this is quite late in the year for a hatch, but it has been hard to track down information on hatch dates for here in Dallas.
The Chinese Tallow tree outside in our yard has thirteen (13) red or brown leaves today. It is one of the first trees to change it leave color in the fall, so I will use this as an index species for fall color this year. Do you know WHY leaves change color? It’s all about different kinds of chemicals found in plant leaves. The green of chlorophyll is the primary color we see much of the year. But because of shortening days, temperature changes, and more subtle changes, chlorophyll production slows to a halt. As the green chlorophyll fades away, some of the other colors, which have been there all the time, begin to become visible and then to predominate. These colors are the evidence of other chemicals important for the plant to produce nutrients. Among these are carotenoids, which help in the photosynthetic process. Tannins, which are actually waste byproducts of cell metabolism, give the brown and yellow colors to leaves, but they are masked by the greens of chlorophyll. Anthocyanins are not produced until the fall, and may have several roles in protecting plants from sun damage and from being eaten. This article discusses some of the possibilities.
A simple explanation of this process is available at the US Forest Service site .
This herbarium has a much more detailed explanation of the same process, if you would like to know more. http://www.butler.edu/herbarium/fallcolor/leaveschange.htm