Our Autumn Color Show
Our Autumn Color Show
by John Schwegman
Illinois lies within North America's eastern deciduous
forest region and shares in its rich heritage of fall foliage
coloration. This year's annual show is underway.
Fall leaf coloration is part of the leaf shedding process
wherein deciduous woody plants drop their leaves that would not
survive the freezing temperatures of winter. We mostly think of
trees as changing color, but many shrubs and vines do also, and
are among our most colorful plants.
As cool temperatures and shorter days herald the coming
winter, plants begin moving sap to their roots to avoid freezing
damage to their stems. The veins that carry sugars made in the
leaves to other parts of the plant are narrowed at this time in
preparation for leaf fall.
Green and yellow pigments are always present in the leaves,
but the green of chlorophyll covers the yellow during the active
growing season of summer. As the days shorten, green chlorophyll
that dies is not replaced and the yellows gradually become
visible.
Sugars produced in the leaves, which normally flow out to
nourish the plant, are restricted in movement by the narrowing
veins and are held in the leaves. Here they convert to red and
orange pigments which color the leaves along with the yellow
pigments until freezing kills and shrivels them.
The yellows appear annually, but the reds, oranges and
purples are dependent on the weather to some extent. Adequate
moisture during the growing season assures abundant sugar
production and bright sunny fall days with cool, but not
freezing, nights are needed to convert some of this sugar to
colorful pigment.
Color intensity in your area will depend on your weather
throughout the summer as well as this fall. Severe drought and
early freezes are major culprits in dimming mother nature's show.
Early to mid October is usually best for northern and
central Illinois color, with southern Illinois usually hitting
its peak the third weekend of the month.
Predominant trees turning yellow in Illinois are ash,
hickory, aspen, tulip tree, and some sugar maples. Leaves of the
native bittersweet vine also turn yellow.
Trees with leaves turning orange-red to orange include sugar
maple and sassafras. Many sugar maples take on the orange-red
appearance, but with some yellow leaves and some pure red leaves
also present. It is probably our most brightly colored,
widespread native tree.
Trees with red leaves include red maple, scarlet oak (and
some other oaks), black or sour gum, sweetgum, and flowering
dogwood. Sweetgum is native only in Illinois only to southern
Illinois and the Wabash River valley, but is planted as an
ornamental tree throughout the state.
Sweetgum is one of our most colorful trees with some leaves
turning red, while others on the same tree turn purple or yellow
or even remain green. Sour gum, on the other hand, always turns
bright red.
Some of our most interesting and attractive red foliage
comes from shrubs and vines.
Common and widespread shrubs like smooth sumac, winged sumac
and aromatic sumac all turn bright red. They are especially
visible because they like to grow on road banks where their
colorful dark red seeds are also attractive.
The climbing Virginia creeper vine is common throughout the
state and turns dark red in early autumn. This member of the
grape family has the habit of clothing old dead trees and fence
posts, which make them appear to be painted red. If you see a
red-appearing tree trunk or fence post you can be certain that
closer inspection will reveal the five-leaflet leaves of Virginia
creeper.
Take the time this fall to enjoy the color and to remember
the natural functions involved with its production. Get out the
camera for some of the most spectacular scenery shots of the year
and take along a field guide to identify as many colorful species
as you can.
# # #
by John Schwegman
Illinois lies within North America's eastern deciduous
forest region and shares in its rich heritage of fall foliage
coloration. This year's annual show is underway.
Fall leaf coloration is part of the leaf shedding process
wherein deciduous woody plants drop their leaves that would not
survive the freezing temperatures of winter. We mostly think of
trees as changing color, but many shrubs and vines do also, and
are among our most colorful plants.
As cool temperatures and shorter days herald the coming
winter, plants begin moving sap to their roots to avoid freezing
damage to their stems. The veins that carry sugars made in the
leaves to other parts of the plant are narrowed at this time in
preparation for leaf fall.
Green and yellow pigments are always present in the leaves,
but the green of chlorophyll covers the yellow during the active
growing season of summer. As the days shorten, green chlorophyll
that dies is not replaced and the yellows gradually become
visible.
Sugars produced in the leaves, which normally flow out to
nourish the plant, are restricted in movement by the narrowing
veins and are held in the leaves. Here they convert to red and
orange pigments which color the leaves along with the yellow
pigments until freezing kills and shrivels them.
The yellows appear annually, but the reds, oranges and
purples are dependent on the weather to some extent. Adequate
moisture during the growing season assures abundant sugar
production and bright sunny fall days with cool, but not
freezing, nights are needed to convert some of this sugar to
colorful pigment.
Color intensity in your area will depend on your weather
throughout the summer as well as this fall. Severe drought and
early freezes are major culprits in dimming mother nature's show.
Early to mid October is usually best for northern and
central Illinois color, with southern Illinois usually hitting
its peak the third weekend of the month.
Predominant trees turning yellow in Illinois are ash,
hickory, aspen, tulip tree, and some sugar maples. Leaves of the
native bittersweet vine also turn yellow.
Trees with leaves turning orange-red to orange include sugar
maple and sassafras. Many sugar maples take on the orange-red
appearance, but with some yellow leaves and some pure red leaves
also present. It is probably our most brightly colored,
widespread native tree.
Trees with red leaves include red maple, scarlet oak (and
some other oaks), black or sour gum, sweetgum, and flowering
dogwood. Sweetgum is native only in Illinois only to southern
Illinois and the Wabash River valley, but is planted as an
ornamental tree throughout the state.
Sweetgum is one of our most colorful trees with some leaves
turning red, while others on the same tree turn purple or yellow
or even remain green. Sour gum, on the other hand, always turns
bright red.
Some of our most interesting and attractive red foliage
comes from shrubs and vines.
Common and widespread shrubs like smooth sumac, winged sumac
and aromatic sumac all turn bright red. They are especially
visible because they like to grow on road banks where their
colorful dark red seeds are also attractive.
The climbing Virginia creeper vine is common throughout the
state and turns dark red in early autumn. This member of the
grape family has the habit of clothing old dead trees and fence
posts, which make them appear to be painted red. If you see a
red-appearing tree trunk or fence post you can be certain that
closer inspection will reveal the five-leaflet leaves of Virginia
creeper.
Take the time this fall to enjoy the color and to remember
the natural functions involved with its production. Get out the
camera for some of the most spectacular scenery shots of the year
and take along a field guide to identify as many colorful species
as you can.
# # #
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