Changing Colorful Leaves

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Changing Colorful Leaves

• and Photosynthesis

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What do autumn leaves and ripening bananas have
in common?
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Photosynthesis
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The Electromagnetic Spectrum
Light we can see!
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Chlorophyll A and B

• Absorbs energy from the sunlight to transform
  carbon dioxide and water into carbohydrates
• Chlorophyll is what gives plants their green
  color

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Carotene and Xanthophyll

• Yellow and orange accessory pigments found in
  plants
• Carotenoids which also participate in
  photosynthesis
• Present all year long

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Seasons

• SUMMER
• Long hours of sunlight
• Good supply of liquid water
• Plants are busy making carbohydrates
• Plants storing food
• Plants growing

• WINTER
• Days are shorter
• Water is harder to come across
• Annuals, Perennials, Evergreens

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• Perennials
• Live for more than two years
• trees and shrubs, and herbaceous plants with
  soft, fleshy stems.
• Woody parts of trees and shrubs can survive the
  cold.
• The above ground parts of herbaceous plants
  (leaves, stalks) will die off
• Underground parts (roots, bulbs) will remain
  alive.
• In the winter, plants rest and live off stored
  food until spring.

• Annuals
• complete their life cycle in one growing season.
• Garden flowers, bulbs
• Die when winter comes, but their seeds remain,
  ready to sprout again in the spring
• Evergreens
• keep most of their leaves during the winter
• have special leaves, resistant to cold and
  moisture loss
• Pine, fir trees, holly
• may continue to photosynthesize during the winter
  as long as they get enough water

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Summer to Fall

• As the bright green fades away, we begin to see
  yellow and orange colors.
• JUST LIKE AS THE CHLOROPHYLL DISSOLVES IN A GREEN
  BANANA TO REVEAL A YELLOW BANANA!
• Small amounts of these colors have been in the
  leaves all along. We just can't see them in the
  summer, because they are covered up by the green
  chlorophyll

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Colors of Fall

• Reds and Purples
• Maples, glucose is trapped in the leaves after
  photosynthesis stops.
• Anthocyanins pigments
• Sunlight and the cool nights of autumn cause the
  leaves turn this glucose into a red color.
• Brown
• - Oaks, due to wastes left in the leaves.