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2006-11-12 11:01:26 · 5 answers · asked by Bob F 1 in Science & Mathematics Botany

5 answers

I like Katie's answer...very thorough...sounds like one of my lectures in my college Botany class...also.....due to chemical changes in the leaves and the slowing of the nutrient flow in the tree/leaves fall off due to the formation of an abscission layer of corky material at the base of the leaf stem or petiole where it attaches to the tree twig. Cutting off water/food and it drys and weakens the attachment, then with a gust of wind shaking it loose to give us some work to rake them up.....oak trees hold tenaciously to their leaves and are often seen with some of their dry browned leaves on them throughout the winter......

2006-11-12 12:42:59 · answer #1 · answered by Sammyleggs222 6 · 0 0

The leaves of most plants contain different pigments, or light-absorbing compounds that make them the color they are. Chlorophyll is the main pigment of plants which makes them have their green color, and is used for photosynthesis. Chlororphyll captures light energy and turns it to chemical energy during photosynthesis. Chlorophyll is the most abundant and important plant pigment and exists in two forms: chlorophyll a and chlorophyll b. They absorb red and blue light but reflect green light, which explains why plants have their green color.

Chlorophyll often hides other plant pigments present in leaves. In the fall, chlorophyll breaks down because of the lack of sunlight used for photosynthesis and allows pigments like xanthrophyll-the pigment that reflects yellow light
and carotene-the pigment that reflects orange light
to show their colors and many other pigments that can be found in leaves.

2006-11-12 19:35:46 · answer #2 · answered by Katie R 1 · 0 0

They are not subject to as much sunlight, thus losing all of their chlorophyll, a chemical that makes them green or greenish. What you are seeing is the leaf's true original color in the fall.

2006-11-12 19:10:56 · answer #3 · answered by careercollegestudent69 4 · 0 0

the pigments in the leafs change

2006-11-12 19:13:17 · answer #4 · answered by gordon_benbow 4 · 0 0

Because they are dead.

2006-11-12 19:04:18 · answer #5 · answered by My two cents 4 · 0 1

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