| ~LTHOUGH we accept as plants are green, their green axiomatic the fact that ,~ pigment, chlorophyll, is remarkable in the biological world. It makes plants, ~te literally, providers of energy to the world s host of living organisms--man all the other animals, and even nongreen plants. For it is chlorophyll that ~s plants the unique ability to utilize the energy of sunlight for the manufac- ~0ffood; and this in turn means that fungi and animals can use plant com- I~ands for energy and for their own building materials, either directly or ~ugh complex food chains. And to man, of course, Plants furnish thousands :other useful products beyond the primary benefits of food. ..We: know from the fossil record that plants appeared on this earth hundreds ~millions of years ago. Although the actual origin of living matter continues ibe a controversial question, it is likely that the earliest living "organisms," hose composition is unknown, derived the energy for growth and reproduc- m by simple chemical means. Presumably they broke down chemical com-~unds in their watery environment; eventually they utilized the sunlight by.~ns of photoreceptive pigments. However it occurred, from some unknown,i"imitive green organism the continuous process of evolution has given us all~e wonderfully diverse and fascinating world of plants we live in today. They found almost everywhere, and the adaptations they have made to special~vir0nments, as the cactus family has to deserts, are as extraordinary as any-~ng in nature. |
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