CHAPTER 3 



ECOLOGY AND THE FLOWERING 

 PROCESS 



The time of flowering is a response to environment; it is an interaction 

 of the plant with its environment. Thus flowering is primarily an 

 ecological phenomenon. Yet comparatively Httle study of the 

 flowering process has been made from the purely ecological stand- 

 point. The mechanisms going on within the plant have proven to be 

 so fascinating that nearly everyone interested in the subject has 

 become preoccupied with this phase of the study. Indeed the bulk 

 of this book will be concerned with the physiological mechanisms 

 of the flowering process. Nevertheless, to try to set the proper 

 perspective, we will devote this chapter to the ecological aspects of 

 flowering: the flowering process in natural habitats as a response to 

 environment. 



The environment itself is a fit subject for extensive study. There 

 are cUmatologists and others who are primarily concerned with 

 temperature, humidity, wind, soil, and Hght as they occur and vary 

 in nature. We do not have space to investigate these topics in detail, 

 but we wiU review seasonal changes in temperature and Ught, since 

 floral initiation is most commonly a response of the plant to these 

 factors. 



Natural Temperatures and Flowering 



Of course, temperatures are extremely variable and dependent upon 

 latitude, elevation, time of year, and various other factors. It is easy 

 to generaUze, however, that temperatures in the tropics are seldom 

 low and that winters become colder as one moves towards the poles 

 or higher in elevation. Few quaUtative plant responses to shght 

 temperature changes are known, and it seems quite appropriate that 

 important steps in the plant's life cycle should not be carefully tuned 

 to shght changes in temperature, since this factor in the environment 



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