By LARRY M. JONES
While I look forward each fall to the cool weather associated with the change of seasons, a wonderful side effect of this transition is the explosion of brilliantly colored foliage.
I love this time of year with delightfully crisp fall mornings and warm and pleasant afternoons. The trees and shrubs change from green to vivid reds, orange, and yellows, with every shade in between. In my opinion, this year has provided the most gorgeous leaf colors I have ever seen in this area. We had a dry autumn with sunny days and cool frostless nights – the ultimate recipe for the most vibrant palate of fall colors.
What causes this dramatic change in foliage color? It is a complex interaction of several factors that affect the three primary pigments contained in the leaves – carotene, anthocyanin and chlorophyll. Shortening of the days and lack of sunlight results in less production of chlorophyll, and allows the green color to fade. At the same time, an increased sugar level stimulates anthocyanin production, which causes the red coloration. While the carotenoids are unaffected by the shortening of the days, they provide primarily the yellows, but also contribute in orange and red hues. Oak trees have an additional chemical, tannin, that is responsible for brown colors.
Each species of tree has its own unique foliage coloration. Here in North Central Texas we have a nice variety that provides an array of colors. Most striking are the brilliant red of the flame-leaf sumacs and the red oak trees. Several species turn bright yellow, perhaps the most notable being the tall stately cottonwoods along rivers and creeks. I am quite blessed down on the “pore farm” to have a unique vista of such fall foliage. The limestone bluffs and hills across the Brazos from my house are covered with brightly colored sumacs, elms, assorted oaks including green live oaks, and various brightly colored low-level ground cover.