Plants And Light

THE PLANT-SKY COLOR (COLOUR) COMPLEMENT

There is something really fundamental about our natural environment that I have noticed but I can find no evidence that it has ever been pointed out. The predominant color (colour) of plants, which is green, complements the colors (colours) of the sky. The green of plants occupy a color niche between the yellow-orange-red of the sun and the blue-violet of the sky. The blue of the sky is scattered light, there is actually a lot of violet in the daytime sky but our eyes are not very sensitive to violet light. Plants must be able to benefit from scattered light, rather than direct sunlight, or trees would not have leaves facing away from the sun.

The spectrum of light from the longest wavelength or lowest frequency is red, orange, yellow, green, blue and, violet. Black is the absence of light, white light is a mix of the entire spectrum and, gray is a mix of black and white. (Note- to avoid continuous use of parenthesis, I am going to alternate the two global spellings of color and colour.)

I theorize that plants are green because it is the major color of light of which the least of it comes from the sky in comparison with the others. This does not include the bright flowers, which are primarily to attract pollinating insects. The colour of an object is actually that light which it does not absorb.

Plants are dependent on the absorption of light and so logically try to absorb the maximum amount of incoming light. By having green as the color that they do not absorb, plants attain an absorption of light that is closer to the maximum. Water is blue because it absorbs light with longer wavelengths first, which is red, and so blue is the colour that is most likely to be refracted back into the atmosphere.

In a quest to attain maximum absorption, plants will move by adaptation toward the color of light that comes from the sky the least. If the sun was green and the sky was red, we can be sure that plants would be blue. The chlorophyll in plants is what gives them their green colour and it seems clear to me that it adapted to become green by adjusting the spacing of it's atoms and molecules over the eons. Of course in inanimate reality, there is no such thing as color. We see colours because the brain interprets certain wavelenghts of light as blue, green or, yellow.

LIGHT AND DARK GREEN

It is well-known that dark shades absorb radiation and light shades reflect radiation. This is why dark shades are dark, because they absorb so much radiation that there is not much to reflect back to our eyes. Light shades are light because they do not absorb much radiation, leaving more to be reflected back to our eyes.

It is therefore logical that plant leaves should be dark, rather than light in shade, to ensure the absorption of the maximum amount of beneficial radiation. this can be clearly seen as most leaves are dark green. The needles of evergreen trees seem to be especially dark in order to absorb the maximum amount of sunlight in the far northern latitudes.

THE DISADVANTAGES OF GRASS

However, there is one great exception to this. Grass is invariably a much lighter green than leaves are. Has anyone else wondered why grass is always a lighter shade of green than are trees? If darker green will absorb more light, which is the goal of plants, why should not grass be a dark green also? This difference in shade between leaves and grass is not due to thickness because the thickness of many dark leaves is scarcely thicker than is a blade of grass.

Another apparent mystery concerning grass is why the leaves of trees are positioned to absorb sunlight but blades of grass grow straight toward the noonday sun. Grass is not perfectly vertical or it would not be visible from above. But grass seems to be at a tremendous disadvantage in both it's light colour and it's directional angle to gain maximum exposure to sunlight in comparison with tree leaves.

THE BOTANICAL LIGHT WELL

I would like to point out a phenomenon that I cannot find has been pointed out before. Blades of grass are parallel to each other and this causes the grass to collectively act as a light well with sunlight. Light reflected by a lightly-shaded stalk of grass is then absorbed by parallel stalks of grass nearby. Parallel blades of grass in a field can get more light by being light in color and thus reflecting the light that falls on the field with other blades of grass.

Trees cannot use this light well method because it's leaves are not parallel to one another and so maximizes it's light absorption by being dark in colour rather than forming a collective light well. A blade of grass, in contrast, absorbs less direct light than leaves but gets more due to reflection from parallel stalks of grass so that they are better off being light in color. Use of this light well method means, of course, that grass must be limited in height.

I also get the impression that grass seems to grow better in lighter soil, which greatly increases the light absorption of stalks close to the ground. Green stalks always seem to be lighter in tone than leaves. Celery, for example is very light in colour. The reeds in ponds tend to be a lighter green than are leaves. I also notice that the leaves of willow trees are a light green and that they tend to hang down parallel, in contrast to other trees. It is likely that the light well effect also takes place to some extent in willow trees.