Not-so-flaming foliage

Colors start to creep into our green landscape as summer slowly loosens its grip. At first, only a few isolated maples turn.

As the process gains momentum in October, more and more trees trade their greens for brighter attire.

Although I have seen some individual exceptions, in general it seems that the colors have not been as spectacular this year. Dry, hot conditions in September have put a damper on the brilliance of our fall foliage.

Normally, dry conditions work in favor of good fall colors. However, cool nights just above freezing in September are essential. The unseasonable warm weather we had this year worked against the development of our flaming foliage.

The process behind the miraculous transformation is quite interesting. Plant leaves contain green photosynthetic pigments called chlorophyll that capture sunlight to make energy for the plants. Almost all plants also contain accessory pigments that aid in photosynthesis.

During the summer, chlorophyll pigments conceal these accessory colors. However, when the amount of daylight shortens and temperatures drop, deciduous trees cease making chlorophyll. The accessory pigments become more visible, giving us our autumn colors.

Carotene, which is also the major pigment in carrots, gives us our orange foliage. Xanthophyll gives us our yellow. Furthermore, the cold weather promotes many leaves to produce a red pigment, anthocyanin.

Aspen, birch, and hickory leaves have a high concentration of xanthophyll. Red maples, sassafras and sumacs have high levels of anthocyanin pigments.

Red maple seems to be the number one contributor to color across our landscape due to its prevalence. However, sassafras is by far the most spectacular. I have seen some individual sassafras trees that have had bright yellow, red, purple, and orange -- all on the same tree!

Sumacs are not that far behind with their brilliant red.

One of our native shrubs, maple leaf viburnum, has some spectacular colors. Too bad it doesn't grow to tree height.

Perhaps my favorite fall foliage of all is that of the tulip poplar. In mid-November when most of the trees have lost their leaves, tulip poplar makes its debut on the fall scene, adding splashes of bright yellow to the drabcolored mountains.

By then the forest is colored only by the greens of our evergreens and the pure white of freshly fallen snow.