THE FLOWER BEHAVIOR OF AVOC^ADOS 



163 



some of the first trees propagated from its buds, and on about 

 thirty Collinson trees of blooming age in grove plantings. For 

 some of these trees observations were continued day after day 

 over a period of more than two weeks. In two instances a single 

 anther valve was found lifted but no jjollcn was present. 



Trees of the Collinson variety appear to be comi^letely im- 

 potent as pollen parents. Their flowers shed no pollen. The 

 fruits maturing on them are all the results of cross-pollination 

 unless they develop without any i^ollination. 



The eesui-ts of pollinations made by hand 



Fruit is not readily obtained on avocados even by the most 

 careful pollinations made by hand. 



In California several thousand self- and close-pollinations 

 were made by hand and in Florida several hundred Avere made. 

 The self-pollinations were necessarily for flowers shedding 

 pollen either in their second period of opening or when the first 

 period had been skipped. The close-pollinations were, of course, 

 made at times when there was an overlap of first-period and 

 second-period flowers on the same tree. These are precisely the 

 kind of pollinations possible when a tree is grow^n in isolation, 

 or is tented, or when a solid block of one variety is grown. Not 

 one of the flowers thus pollinated set a fruit. 



But relatively few cross-pollinations succeed. In making such 

 pollinations flowers which were in the height of shedding pollen 

 were taken from one variety and their pollen applied directly by 

 rubbing the pollen masses over the stigmas of flowers of another 

 variety open for the first time. These are the pollinations which 

 flower behavior indicates are most likely to be most proper. 

 With the assistance of various students of Pomona College and 

 particularly of Mr. Howard Ijorbeer, the writer made 3,430 such 

 pollinations in California. These involved chiefly the varieties 

 Dickinson, Puebla, and Taft of the A varieties and Fuerte, Har- 

 mon, and Northrop of the B varieties. In February 500 of these 

 pollinations were made, in March 1,280, in April 885 and in May 

 765. Alost of them were made while there was much delayed 

 action in flower behavior and while very little fruit was setting 



