THE FLOWER BEHAVIOR OF AVOCADOS* 



A. B. Stout 

 (with plates 24-28 and charts 1-10) 



TABLE OF CONTENTS 



Introduction 145 



How synchronous dichogamy is achieved in avocados 146 



The two types of daily sequence in the alternation of sexes 149 



List of the most important varieties according to the daily sequence 



of dianthesis 151 



The cycles of dianthesis of the sets of flowers 153 



Individual or varietal dilferences in flower behavior 155 



Irregular and abnormal flower-behavior 157 



The regulation of the flower mechanism 159 



Evidence bearing on the evolution of dianthesis and synchronous 



dichogamy in avocados 161 



The male sterility of the Collinson variety 162 



The results of pollinations made by hand 163 



Fruit-setting by tented trees with bees enclosed 165 



Remarks on the interi^lanting of avocados 169 



Acknowledgment 172 



Literature bearing on flower behavior of avocados 172 



In avocados tlie development of the two sexes in the her- 

 maphrodite flowers is so regulated that the many flowers open on 

 the entire tree function only as females during certain hours of 

 the day and only as males during certain other hours of that 



* Avocados or alligator pears are evergreen trees of the laurel family (Lauraceae) 

 indigenous to tropical America. Those in cultivation at the present time embrace at 

 least three somewhat distinct races derived evidently from what has been considered 

 as two somewhat closely related species of the genus Persea. Apparently avocados 

 were grown during early pre-Columbian time as an important food crop in Central 

 . America and Mexico with later introduction into portions of South America and the 

 West Indies. More recently their culture has spread into various tropical countries 

 of the Old World and particularly has their culture become an important horticul- 

 tural industry in Florida and California, with promise of much further development. 



145 



