The weather changed from Autumn to winter with the wind chill that roared in Saturday afternoon from the South West, occasionally twirling around to the North to utterly confuse us. Overnight Mother Nature has begun her seasonal foliage change which always provides a slow-moving breath-taking picturesque display.
Within a few weeks the Caddo Maples will
begin to change, reminding the gardener the first freeze will occur within a
week. They are unusual in that all of their leaves do not freeze-fall; much of
their glorious foliage, although crisp, remains tree-bound until Spring. Just
as their color change predicts a coming freeze, these last leaves foretell the
arrival of Spring as they are literally tossed from the tree when it is
expected to arrive. As the Maples had predicted last year, our first deep
freeze roared in early one morning and suddenly Winter was upon us… in a most
vengeful manner.
Trees lose their leaves to give additional
sunlight for warmth during the cold winter months and Nature has provided us
with a stunning visual as a parting gift. Although the following explanation
will be a vast over simplification, it may provide insight into the foliage
change. During the spring and summer, the trees use their leaves to collect air
and water to turn it into food. The process, called photosynthesis means
‘putting together with light’ so as the days shorten and daylight diminishes,
the gathering process ends. The leaf is no longer necessary to the tree and
begins its transformation providing breathtaking color for a brief moment in
time.
The chemicals chlorophyll and carotenoids are
present in the leaf cells throughout the growing season with chlorophyll making
leaves the bright green color. As daylight decreases in autumn, chlorophyll
production stops and the chlorophyll disappears. With the loss of chlorophyll
the carotids, which have been there all along, become visible and display
lovely yellow leaf color. Lastly the anthocyanins arrive and take center stage,
ushering in the vibrant reds we associate with Autumn.
Anthocyanins, which are glucose, are singularly responsible for the brilliant
hues of purple, crimson, and scarlet. They are a fickle lot, insisting on warm
sunny days and crisp evenings to slow the closing of the leaf veins and trap
excess sugar produced at this time… if the weather does not comply to their
demand, lackluster reds are produced.
Shade and the foliage show are not all the
leaves have to offer… their parting gift is perhaps the most important. As the
leaves drift from the trees and collect below they continue to work by slowly
decomposing. Over time this process adds nutrients to create a dark rich soil
which nourishes the fledgling the saplings as they grow to become forest giants
like their parents. Nature is always at work, regardless of the season.
