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If
only we could capture the beauty of autumn and hold it to
our hearts all winter long! One of the spectacular features
of fall is the wonderful coloring of tree leaves. The more
curious among us might wonder just how does fall color develop
in trees? It's a story that's been told before, but here it
is one more time.
The
purpose of plant leaves is to harness the sun's energy to
feed the tree. It does this by way of the chloroplasts in
leaf cells. The chloropalsts contain the green plant pigment,
chlorophyll. This pigment enables the leaves to capture the
sun's energy to make sugars and oxygen from carbon dioxide
and water. During the growing season the chlorophyll in present
in abundant quantities. As the weather turns cool the fall
and the days shorten, the leaves stop producing chlorophyll.
Some
tree and shrub species are genetically capable of taking the
carbohydrates left in the leaves and making them into anthocyanins.
These are the red pigments responsible for the reds, pinks,
and purples in leaves. As the chlorophyll begins to break
down, the newly formed anthocyanins become apparent. Other
plants are not genetically capable of making the anthocyanins.
When the chlorophyll breaks down in these plants, the leaves
reveal the more stable orange and yellow pigments (carotene
and xanthophyll). Brilliant oranges come from a mix of anthocyanins
along with the carotenes and xanthophylls. Trees that don't
"perform" with remarkable colors lose all their
pigmentation at one time and usually over a short span.
What
are the weather conditions that favor the best fall color?
Autumn weather that favors good production of soluble carbohydrates
in the leaves will lead to more splendid fall coloring. Dry,
sunny, and cool conditions but not lots of heavy frost are
best for bringing out the reds, oranges, and bright yellows.
If plants that are supposed to show spectacular color, don't...
then their location or general health may be the problem.
Sunlight is generally needed for development of fall color,
especially the reds. If a plant is shaded, development of
fall color will be deficient. If the plant is experiencing
stress, such as drought stress, fall color may be lacking.
A plant that is not cued into the advent of fall because it's
still growing vigorously due to heavy watering and fertilization
late in the growing season, may also lack brilliant color.
Can
you remember pressing brightly colored leaves between sheets
of waxed paper to preserve their colors? It's one of those
experiences of life that no one should miss. Here's how you
do it. Place autumn-colored leaves between two layers of wax
paper. Cover with an old towel or cloth rag. Press the fabric
with a warm iron, sealing the wax paper together with the
leaf in between. Cut your leaves out, leaving a narrow margin
of wax paper around the leaf edge.
Of
course that's the old-fashioned way of doing things. You can
preserve fall leaves in your microwave oven. Choose fresh
leaves with the brightest colors. You don't want fallen leaves
that have already started to dry. Take separate leaves or
small twigs and place them in the oven on top of two pieces
of paper toweling. Cover them with one sheet of paper toweling.
Run
the oven for 30 to 180 seconds. The drier the leaves, the
less time they will need. Observe caution, as you could start
a fire in your microwave if they "cook" too long.
Be attentive. Leaves that curl after removal, have not been
dried enough. Leaves that scorch, have obviously been left
in too long. Let the leaves dry for a day or two and then
finish the leaves with a sealant, such as an acrylic craft
spray.
You
may get even better results if you use the microwave and silica
gel for drying. Place a 1.25 inch layer of floral silica gel
in the bottom of a cardboard box. Place the leaves lying flat.
Leaves should not touch and should be at least 1.25 inches
away from the sides of the box. Cover the leaves with a 1.25-inch
layer of gel. Place the uncovered box in the microwave. You
want the microwave to operate at about 200 to 300 watts so
if your microwave has 2-10 settings operate it at level 4.
If the oven only has three to four settings, it should be
set at half. If your oven has a high to defrost options, set
the microwave on defrost. Estimated drying time is 2.5 minutes
if you're using a half pound of gel and about 5 minutes if
using two pounds of gel.
Yet
another way to preserve the leaves is to submerge them in
a solution of glycerin and water. Use a mixture of one part
glycerin to two parts water. Place the mixture in a flat pan,
and totally submerge the leaves (in a single layer) in the
liquid. You'll have to weight them down to keep them submerged.
In about two to six days they should have absorbed the liquid
and be soft and pliable. Remove them from the pan and wipe
off all the liquid with a soft cloth. Done correctly, the
leaves will remain soft and pliable indefinitely.
So
take some time with the children in your life and go out and
collect some of the treasures of fall. It's something they'll
remember for the rest of their life... I know I have.
Click
for U.S. Regional Fall Foliage Update
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