162 



THE FLOWERING PROCESS 



4-0 



3-0 c> 



o 



1-0 



35 

 TIME IN DAYS 



Figure 9-4 



Size and growth rate of cocklebur leaves as a function of time. Leaves 

 which were 1 cm long at the beginning of the experiment, were measured 

 by Jean Livingston for 33 days, beginning on September 5, 1962. The 

 length of the midrib was determined, but this value is squared in the 

 figure to more closely approximate leaf area. Points represent averages 

 for 10 plants. Growth rate was determined by measurement of the slope 

 of the curve drawn through the points. Data previously unpublished. 



then anything which will influence expansion will influence sensitivity. 

 There are, of course, experimental ways to investigate some of these 

 interesting possibilities. 



Temperature Effects 



1. The Inductive Dark Period at Various Constant Temperatures 

 Since the very term synthesis implies a series of chemical reactions, 



we would expect the whole process to be quite sensitive to temperature. 



Interestingly enough, the subject has very seldom been investigated. 

 Realizing this, we set up an experiment during January 1962 in 



our growth chambers in which groups of plants were given dark 



