When leaves are not green...

How Does a Japanese Maple Tree Photosynthesize?

Japanese maples are prized for the deep mahogany color of their leaves. Recalling lessons in botany, we may wonder how it is that these trees photosynthesize since chlorophyll, the green leaf pigment responsible for photosynthesis, does not appear to be present. 


An understanding of leaf pigments in general can explain this phenomenon.

Identification

• Japanese maples differ from other maple trees in that their leaves, depending on the cultivar, range from red to purple in color. According to Virginia State University Extension, this color is most vibrant in early spring, when leaves are first emerging, and in late fall. During the height of summer, the leaves turn almost green. Trees grown in shady locations may also develop green leaves.

Photosynthesis

• Photosynthesis is the process by which plants produce their own food in the form of carbohydrate, using sunlight, water and carbon dioxide. Light energy is converted to chemical energy. Regardless of how much water, carbon dioxide and soil nutrients are provided, a plant will suffer if it cannot photosynthesize its food. Japanese maples in shady locations require more chlorophyll to achieve sufficient photosynthesis, so their leaves tend to look greener year round.

  Chlorophyll

  • Chlorophyll gives plants their color by absorbing red and blue light while reflecting green. It is unique in that it can also store some of the solar energy in a latent form for later use by the plant. During photosynthesis chlorophyll is continually used up and must be replaced.

  Other Pigments

  • Carotenoids, which reflect yellow and orange, are secondary pigments in leaves that absorb light. A third class of pigment, anthocyanins, are responsible for all the red, blue and purple colors of leaves and fruits. These are the pigments in Japanese maples. Since chlorophyll is the least chemically stable of all the pigments, the others provide protection to chlorophyll from excess sun radiation by absorbing some wavelengths of light.

  Significance

  • Japanese maple trees, as with all other plants of red and blue hue, contain high amounts of anthocyanins along with the chlorophyll that is necessary for plant life. Although we may see mostly red color on the leaves, there is still sufficient chlorophyll to carry on photosynthesis. It is a matter of what pigment predominates as to what color our eyes see. The fact that we cannot see green does not mean that there is no chlorophyll present.

    Seasonal Changes

    • During the early spring, anthocyanin pigments predominate, with new leaves being formed by stored energy within the tree sap. As summer arrives, photosynthesis is at a high rate and the increased amount of chlorophyll masks the anthocyanin pigments so that we see green leaves tinged with red. Again in the fall leaves turn redder as photosynthesis declines, the amount of chlorophyll diminishes, and the anthocyanins are more visible.

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    Read more: How Does a Japanese Maple Tree Photosynthesize? | eHow.com http://www.ehow.com/about_6688901_japanese-maple-tree-photosynthesize_.html#ixzz1zfRpZWid