184 



]MEMOIRS OF THE 2^EW YORK BOTANICAL GAKDEif 



EXPLANATION OF CHART 1 



In this chart, as in those following, the continuous line indicates for 

 each variety the entire time when flowers were open for the first period. 

 The dots indicate the time during- which flowei-s of the second period of 

 opening were shedding pollen and the dashes show the intervals of open- 

 ing and closing before and after pollen was being shed. As a rule the 

 pollen was being shed most abundantly near the middle of the period 

 covered by the dots. 



This chart is a record of the flower behavior of 18 varieties for one and 

 the same day. After a minimum of 57° during the preceding night and 

 an early morning fog the day was clear and breezy with a maximum 

 temperatiire of 85° reached sometime after noon. This record is typical 

 for days of good weather during February, 1925, in Florida. 



Every variety studied on this day had two sets of flowers open as indi- 

 cated. For Perfecto, Grande, and Harmon, there was a short interval 

 when pollen was being shed while first-period flowers were slightly open, 

 otherwise there was no overlap of first-period flowers open while second- 

 period flowers were open and shedding pollen, and no opportunity for 

 self or close-pollination. Thus in avocados, the normal flower-behavior 

 greatly limits self-fruitfulness. 



The varieties fall into two groups. Those of one group (A } are female 

 in the forenoon and male in the afternoon. The others (Group B) are 

 male in the forenoon and female in the afternoon. There is thus a most 

 decided adaptation for reciprocal cross-pollination between certain varie- 

 ties of the two groups. 



