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Dear
Mr. Lofland's 1st grade class,
To understand why the grass is green we have to start with
light. Colors come from light. Any object you see, including
green grass, is a color because the light is either bounced
back (reflected), taken into (absorbed), or passed through
(transmitted) that object. If all the light is absorbed the
object is black. When you can see color through something
like a glass of water or a swimming pool the light has been
transmitted. The color of light that is reflected is what
makes the object have that color. An apple is red because
it reflects red light, Shrek is green because he reflects
green light, and Aubie has lots of orange because he reflects
orange light.
So, grass is green because it reflects green light. But why
does grass absorb all the other colors of the rainbow and
reflect the green light? This is because grass contains chlorophyll
- a greenish compound that takes sunlight and turns it into
the grasses' food. We get our food by eating plants and animals,
but plants get their food from the sunlight. When plants use
the sunlight and chlorophyll to make food the process is called
photosynthesis. The fact that plants make their own food using
light was first discovered over 225 years ago.
So, grass is green because it reflects green light, and that
green color comes from chlorophyll. You may have noticed,
however, that in the winter a lot of our Alabama grasses are
not green - they are brown. Our southern grasses (bermudagrass,
centipedegrass, St. Augustinegrass, zoysiagrass) are warm-season
grasses - they are happiest in the hot, humid days of May,
June, July and August. When it gets cold they go dormant,
turning brown and not growing until it warms up in the spring.
That's why your yard may look dead in the wintertime. That
brown colored turf is not dead grass - it's just sleeping
until springtime when it will turn green again. If it's winter
time and the grass is still green, your turf is what we call
a cool-season grass (tall fescue, perennial ryegrass), which
is happiest growing in cooler fall months. In fact, to keep
grass looking green all year long in the south we might plant
cool-season perennial ryegrass into the brown, dormant bermudagrass.
That way when you play fall and winter soccer, or watch the
Tigers play football, the grass is green even if it is October,
November, or December!
Thanks
for your question,
Aubie and Dr. Guertal
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