THE FLOWER BEHAVIOR OF AVOCADOS 



155 



tlie flowers will open to shed pollen the next forenoon (interval 

 of 12 hours) and the others will remain closed for an interval of 

 36 hours (see B 3 in chart 5). Then, on any given forenoon, 

 part of the llowers of two different sets shed pollen. Those of 

 the older set (of 36-hour interval) begin shedding pollen some- 

 what the earlier. The three types of behavior (B 1, B 2, and 

 B 3) may all be observed in a single day for different varieties 

 growing side by side in the same grove. 



In considering the sequence of complete cycles of sets of 

 flowers, the varieties of the B group show the greatest diversity. 

 The simplest sequence seen among avocados is that with the 24- 

 hour cycle and the 12-hour interval (see B 1) and the most com- 

 plex is in the splitting of single sets into groups having 24-hour 

 and 48-hour cycles. 



It would seem that marked changes in the cycles of sets 

 such as are described above must have a profound influence on 

 the ability of flowers to function in fruit-setting entirely inde- 

 pendently of jDollination. 



No attempt is here made to indicate cycles of anthesis during 

 periods when off stride and irregular blooming breaks the 

 normal daily alternation and its regular sequence. 



Individual, or varietal differences in flower behavior 



The various charts recording normal daily alternation of sets 

 (charts 1-4) reveal that noticeable variations exist among dif- 

 ferent varieties of each group A and B regarding the particular 

 hours in the day when the sets of flowers are open. 



Thus, for the A varieties studied on February 24 (chart 1), 

 there was a difference of two hours in the time when the different 

 sets of first-j)eriod flowers began to open. The length of time 

 these sets were open also varied ; for Atlixco the time was from 

 9:00 A. M. to 2:00 P. M., while for Pinelli the period was from 

 11 :00 A. M. to 2 :15 P. M., a difference of nearly two hours. 



Even more marked differences are seen for the sets of first- 

 period flowers among varieties of the B group. For some varie- 

 ties, such as Queen and Meserve, the first-period flowers begin to 

 open early in the afternoon, for others this set starts to open 

 late in the afternoon. 



