The Light Plans Of Plants

In my posting "Plants And Light" on this blog, I explained the very simple but undocumented reason why plants tend to be green. An object reflects those colors (colours) that it does not absorb and the colours (colors) that are reflected away are what appears to our eyes. Plants try to absorb as much light as they can and since green is the color (colour) of light of which the least comes from the sky, plants tend to be green.

I have also noticed that plants have five separate "light plans" that they use. This refers to the method that a plant uses to harvest the light that it requires. These five light plans are: 1) Grass 2) Raised Grass 3) Indirect 4) Direct and, 5) Flowers.

As I pointed out in that posting, grass depends on the sharing of light among the blades of grass. This is why grass is a much lighter shade of green than the leaves of trees. This is necessary because grass is essentially vertical in stature in relation to the incoming sunlight. A blade of grass reflects, rather than absorbs, much of the light that falls upon it but in return gets light reflected back to it from fellow blades of grass. This causes the grass as a whole to absorb more light from the sun than if it were darker in color (colour).

Willow trees, with their sword-shaped leaves hanging vertically, is an example of the Raised Grass light plan. This plan operates essentially the same way as the grass on the ground but is raised above the ground in a tree. Willow leaves have a darker outer side to absorb light but a lighter shade inner side to reflect light to other leaves, just as grass does. Even the outer portion of willow leaves are light in shade in comparison with other trees and this is another example of how it uses the Raised Grass plan.

Evergreen trees also use the Raised Grass Plan. The needles of evergreen trees resemble blades of grass in terms of collecting light. But evergreen needles tend to be dark and so do not rely on the sharing of light among themselves. Instead, evergreens rely on the reflection of sunlight to them off the snow when the sun is low in the sky during the winter months.

The Indirect Light Plan is that used by deciduous (leaf-bearing) trees in temperate latitudes. This means that leaves on these trees can just as easily point away from the sun as toward it. Deciduous leaves absorb light that has been scattered all around as well as light directly from the sun if the leaf happens to point in that direction. These leaves are dark green and thus do not operate in the same way as grass at all.

The Direct Light Plan is possible only in the tropics where the sun is close to being directly overhead. Palm trees are an ideal example of this plan. Their light-absorbing surface is much less than that of trees using the other light plans. but this is more than made up for by the fact that their leaves or fronds point directly in the direction of the sun overhead. Their color (colour) is a dark green since no sharing of light is necessary.

The fifth and final light plan is that of flowers. I will broadly define flowers for the purpose of this article as any plant whose light-gathering surface is a colour (color) other than green. These plants are inevitably small in scale and number but represent a light "subculture" in the plant world.

The process that must have brought flowers into existence is that if a plant is sorrounded by a great number of other plants so that it is largely blocked off from sunlight in it's lush green sorroundings, there comes a point where the plant is better off absorbing the green light reflected by the plants all around it instead of relying mainly on light from the sky. To accomplish this, the light-gathering surfaces of these plants would have to be a color (colour) other than green, since a surface reflects those colours (colors) of light that it does not absorb. Thus, small plants developed in colors (colours) other than green.

This caused these plants to stand out visually which led to pollination by bees. Dandelions are yellow, which means that they reflect away much of the light which comes from the sun instead of absorbing it. But they get all the light they need by absorbing that light reflected by sorrounding greenery. Notice that dandelions are almost inevitably found amongst grass where they join in the light-sharing among grass. I consider the fact that plants with light-gathering surfaces other than green ones are inevitably small in scale so that they can absorb light from sorrounding green plants as proof of my Plants And Light hypothesis.