Dissipative Structures - Chapter 8 – excerpt from page 178Green plants play a vital role in the flow of energy through all ecological cycles. Their roots take in water and mineral salts from the earth, and the resulting juices rise up to the to the leaves, where they combine with carbon dioxide (CO2) from the air to form sugars and other organic compounds. (These include cellulose, the main structural element of cell walls.) In this marvelous process, known as photosynthesis, solar energy is converted into chemical energy and bound in the organic substances, while oxygen is released into the air to be taken up again by other plants, and by animals, in the process of respiration.
By blending water and minerals from below with sunlight and CO2 from above, green plants link the earth to the sky. We tend to believe that plants grow out of the soil, but in fact most of their substance comes from the air. The bulk of the cellulose and the other organic compounds produced through photosynthesis consists of heavy carbon and oxygen atoms, which plants take directly from the air in the form of CO2. Thus the weight of a wooden log comes almost entirely from the air. When we burn a log in a fireplace, oxygen and carbon combine once more into CO2, and in the light and heat of the fire we recover part of the solar energy that went into making the wood.
Source: The Web of Life: A New Scientific Understanding of Living Systems, Pages: 178
Contributed by: Hannes