CHAPTER V 

 THE EVOLUTION OF PLANTS 



I THE NATURE OF PLANTS 



What is a plant? Thus far, the plants we have mentioned (trees, 

 farm crops, garden vegetables) are obviously plants. For general 

 purposes in denning a plant we might adapt the pattern of the 

 primary teacher whose young pupils were amazed when he called a 

 spider an animal. They were in the habit of thinking of an animal as 

 something with four legs and hair. "Is a spider a plant?" the teacher 

 inquired. "No." "It it a mineral?" "No." "Then what else could 

 it be but an animal?" 



Plant-Animal Differences. It is not important here whether slime- 

 mold is plant or animal. The scientists are free to continue their 

 arguments. The Euglena, which takes in food much as an animal does, 

 but also contains chlorophyll and makes some of its own food, is ad- 

 mitted to be both plant and animal. Actually, it is difficult to define a 

 plant. Not all of them contain chlorophyll and make sugar from air 

 and water; yeasts, Indian Pipe, golden dodder, and mushrooms do 

 not, to mention a few. Not all plants have leaves, nor stems, nor even 

 roots. Not all plants are anchored to the earth, 

 they have, in general, less mobility than animals. The confusion 



We can say that plants are more carbohydrates than protein, and 

 down in the lower orders gives strong suggestion that plants and 

 animals may have a common ancestry. When we get out of the micro- 

 scopic jungle there is less doubt as to whether an animal is an animal, 

 or a plant a plant. 



What is life? Plants, we say, are organic; they are alive. Just 

 what life is, again is difficult to define. It apparently is closely linked 

 with chlorophyll, and this is another reason for thinking that animal 

 life may be derived from plant life which logically had to come first. 

 As to the original spark which started life off, we end up with what 

 Dr. H. A. Morgan calls the "creative concept," 1 which he and most 

 people attribute to God, others to "Nature." 



This "creative concept" was brought to bear on the electrical, 

 gaseous void which was to become the elements and the universe. The 

 heavenly bodies took form and developed into the marvelous organiza- 

 tion which we slowly have been discovering through science. The 



JMorgan, H. A., From a chart published by Tennessee Valley Authority, 

 Knoxville, Tenn., (no date). 



48 



