PART II 

 MORPHOLOGY AND LIFE HISTORY 



I. MEANING OF THE TERMS 



A. Morphology. Under Part I we considered various 

 physiological processes, the primary result of which was 

 to maintain the life of the individual plant. Most of 

 those processes were found to be carried on by all 

 plants. It is common knowledge, however, that plants 

 differ widely from each other in both structure and 

 habit of life. In other words, we recognize the fact of 

 variation. This means that different plants solve the 

 same problems of life in different ways. That phase of 

 botany which concerns itself with a comparative study 

 of structures, and seeks to interpret the structural value 

 of an organ, no matter how it may be disguised, is 

 termed the science of form, or morphology. 



B. Life History. Every plant, in the course of its exist- 

 ence, passes through a series of changes, in orderly 

 sequence. Like an animal, every plant begins life as 

 a single cell, the egg, or the equivalent of an egg; 

 the egg (except in some of the lower plants) develops 

 into an embryo, and the embryo grows and develops 

 into an adult. The adult in turn, produces an egg, 

 like the one from which it came, thus completing one 

 life cycle and initiating another. These various 

 changes constitute the life history of the individual. 



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