Why Do Leaves Change Color?

The green color of leaves comes from the pigment called “Chlorophyll,” which helps with photosynthesis. 

Leaves change color in the fall due to changes in the amount of daylight and temperature.

The days get shorter, and the temperature drops. The trees prepare for winter by stopping the production of chlorophyll. 

The green color disappears, and other pigments become visible.

Types of Color Pigments

The color-causing pigments in leaves are primarily chlorophyll, carotenoids, and anthocyanins.

  • Chlorophyll: This is the pigment responsible for the green color of leaves during the growing season. 
    • Chlorophyll production slows down and eventually stops in the fall
  • Carotenoids: These pigments produce yellow, orange, and brown colors in leaves. 
    • They are present in chloroplasts along with chlorophyll.
    • When chlorophyll breaks down in the fall, carotenoids become more visible, creating vibrant yellows and orange colors.
  • Anthocyanins: These pigments produce red, purple, and blue colors in leaves. 
    • Anthocyanins are not always present in leaves.
    • They are produced under certain environmental conditions, such as exposure to sunlight and cool temperatures. 
    • Anthocyanins act as sunscreen for leaves, protecting them from damage as they prepare to fall off the tree.

Do All Leaves Change Color?

No, not all leaves change color in the fall.

Deciduous Trees: Deciduous trees change colors and shed their leaves. 

  • Maple trees: The leaves of maple trees turn vibrant shades of red, orange, and yellow in the fall.
  • Oak trees: Oak trees change colors from red to brown to bronze.
  • Birch trees: Birch trees often turn bright yellow in the fall.

Evergreen Trees: Evergreen trees retain their leaves or needles year-round and do not change color.

  • Pine trees: Pine needles remain green throughout the year.
  • Fir trees: Fir trees retain their green needles in all seasons.
  • Spruce trees: Spruce needles also stay green year-round.

Fun Facts

Here are some interesting facts about leaves:

  • Evergreen needles are coated with wax to protect them from the cold, which also helps protect the chlorophyll.
  • The red and purple colors are due to sap and sugar trapped in the leaves.
  • The orange colors come from beta carotene, which gives carrots and pumpkins their color.
  • The brown shades of leaves come from tannins that protect the leaf tissue

Review

Let’s quickly recap what we learned as plant detectives:

  • What pigment gives leaves their green color? Chlorophyll 
  • Which two factors determine color changes in leaves? Amount of daylight and Temperature
  • What pigments produce yellow, orange, and brown colors in leaves?  Carotenoids
  • What colors do Anthocyanins produce in leaves? Red, Purple, and Blue
  • All leaves change color in the fall. True or False? False
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