CLIMATE AND PLANT GROWTH. 



51 



recorded in the spruce-fir type, while in the central type the physio- 

 logical temperature efficiency was intermediate. Since a habitat with 

 low -growing temperatures requires a greater number of days for the 



Temperature Above 40 F. 



' Average Daily Mean Temperature 



FIG. 27. Relation of temperature to time of first appearance of blossoms in peas. 



plant to reach a given stage of maturity than a warmer situation, it 

 is evident that the physiological temperature indices would be in in- 

 verse ratio to the time required to bring the plant to a given stage of 

 maturity. 



