CLIMATE AND PLANT GROWTH. 



53 



EFFECT OF TEMPEKATUKE AS INDICATED BY WATEK EEQUIREMENT PER UNIT OF 



LEAF AREA. 



The water requirements per unit of area of the chief food manufac- 

 turing agents of plants — the leaves — may be used as an index of the 











^ 







^ — "" 





sz* 







^'' 











39 



<C?a^> 



68S 



SO 







660 







ss ■ __ ____ 



S2 











































63 



Oak-brush 



Aspen 



Spruce-f/r 



. Days for appearance of heads 



Temperature above 40° 



_ A verag e c/ai/y mean temperature 



Fig. 29. — Relation of temperature to time of first appearance of heads of brome grass. 



efficiency of the leaves as users of water. The leaf length is used in- 

 stead of actual leaf area in the data given below, since, as has been 

 previously shown, it is proportional to the actual area. 



