22 



THE FLOWERING PROCESS 



Figure 2-2 

 The possible combinations of response type. There are 777 visible and 

 other solid blocks, each representing a possible combination of response 

 types. Obviously some would not be expected to occur, and other 

 possible categories are not shown, so the number is only an indication 

 of possible magnitude. 



Fig. 2-2. Temperature and day-length interactions are, of course, 

 impossible in day-neutral plants since they have no day-length 

 response, and hence this is omitted from the figure. All other cate- 

 gories would be accounted for, even though we might consider them 

 as being rather unhkely. Multiplying by the number of categories 

 horizontally, vertically, and in the third dimension, we see that there 



