2 THE FLOWERING PROCESS 



2. Response of an Organism to its Environment 



3. Biological Timing 



4. Biochemistry 



5. Morphogenesis or the Origin of Form 



A brief discussion of these five topics now will serve as an introduc- 

 tion to the more detailed discussion of the flowering process which 

 follows. We think of flowering in terms of component steps or events 

 which are taking place within the plant and which ultimately lead to 

 the formation and development of flowers. The whole point of the 

 first topic is that these steps may vary considerably from one species 

 to another. Thus in discussing the last four topics (and in the last 

 six chapters of this book) we shall consider the steps primarily as 

 they are thought to occur in our "type" plant, the cocklebur, although 

 deviations will often be mentioned. 



1 . Diversity and Uniformity of Biological Material 



In considering this topic one cannot help feeling somewhat like a 

 pendulum. It is quite obvious that the world of living things consists 

 of a myriad of diverse forms. The list of known species extends into 

 the millions and the diversity is enormous. Consider the protozoa, 

 jelly fish, sponges, flat, round, and segmented worms, starfish, shell 

 fish, snails, shrimps, finned fish, lizards, birds, mammals, and all the 

 other sundry groups of animals. Then think of the bacteria, many 

 kinds of algae, fungi, mosses, liverworts, ferns, conifers, and flowering 

 plants. The taxonomist estimates that we shall one day know three 

 to five million kinds of insects alone. Thus on one swing of the 

 pendulum we are fully aware that there are many kinds of living 

 things. 



Yet the significant generalization of modern biology is that all of 

 these various organisms have a number of important and basic 

 functions in common. This is most striking when one considers the 

 biochemistry of the cell. Respiration, for example, proceeds along 

 essentially the same metabolic pathways in all living things, and this 

 also seems to be true for many other processes such as protein 

 synthesis, fat metabolism, etc. So the other end of the pendulum's 

 swing is the concept that living things are really all very much alike. 

 Is this true in the flowering process ? At this stage of the game we 

 simply do not know. Some workers have assumed that it was true — 



