160 



THE FLOWERING PROCESS 



Growth rate 



20 



15- 



05 



o 



tr, 



8-0 

 7-0 



6-0 



5-0 S 



I- 



4-0 ^ 



o 

 3-0 u^ 



2-0 



1-0 



-0 



12 3 4 



LEAF NUMBER 



4 8 12 16 20 



APPROXIMATE TIME IN DAYS 



Figure 9-3 



Relative leaf area (leaf length squared), "growth rate" derived from 

 this, and Floral Stage as a function of leaf number. See Fig. 5-4. 



a function of leaf number. The square of the length is more nearly 

 proportional to the area of the leaf than is the length itself. If we 

 imagined that under uniform growing conditions the plants grow 

 at a fairly constant rate and produce new leaves at a fairly constant 

 rate, then we might replace the scale on the bottom of the graph with 

 time instead of leaf number. That is, if a new leaf is produced once 

 every four days (the approximate rate), then the intervals on the 

 graph which show leaf number might show time in 4-day periods, as 

 indicated. The curve then becomes a growth curve, showing size of 

 the leaf as a function of its age. Such curves have often been obtained 

 with various organisms. 



Plotting the increments of growth during unit time intervals 

 against age of the leaf, a curve showing growth rate as a function of 

 time is produced. This curve may also be obtained by measuring the 

 slope of the size curve (slope is expressed as size units per unit time), 



