92 



trees the stigmas remained apparently receptive during the second 

 period opening, so that there was a good possibility of the transfer 

 to them of pollen from the same flower and of other flowers of the 

 same or the three neighboring trees in class B, the irregular char- 

 acter of the first opening made the accomplishment of what we 

 may term the "legitimate pollination" of these flowers by the two 

 neighboring class A trees extremely unlikely. When I examined 

 these four trees at the end of March I could find only a single im- 

 mature fruit in the whole group, despite the myriad blossoms each 

 tree had expanded. 



Stout and Savage and Robinson have demonstrated that ab- 

 normal weather, especially a cold spell, may cause great dis- 

 turbances in the daily periodicity of the flowers, amounting some- 

 times to the complete inhibition of the first period opening. The 

 result is a set of flowers which exhibit only a single period of 

 anthesis, when the pollen is shed. The peculiar behavior of the four 

 trees in my third group was certainly not conditioned by atmos- 

 pheric conditions, for it occured during warm, bright weather as 

 well as on cloudy and rainy days, and was the usual behavior of 

 the trees in question. It may be noticed in passing that the two 

 trees of group II show an approach to the condition of group III 

 in their relatively brief first period opening (less than 3 hours) 

 followed by a second period of anthesis over twice as long on the 

 following day. 



It is hardly an exaggeration to state that a large avocado tree 

 produces millions of flowers each season, and only an exceedingly 

 small proportion of these set fruit even under the most favorable 

 conditions. The normal fate of the flower is then to fall shortly 

 after closing for the second time — by the second day after this 

 final closing most have been shed, by the third day practically all 

 save the few which set fruit. During the height of the flowering 

 season there is a constant shower of effete blossoms, and the ground 

 beneath the trees is thickly strewn with them. The continuous drop- 

 ping of the closed blossoms reminds one of the sifting down of the 

 corollas of grape flowers beneath a wild vine which is coming into 

 full bloom. As a breeze shakes the bare limbs, the pattering of fall- 

 ing flowers upon the dry- leaves which cover the ground beneath 

 the tree sounds like the rustling of the first flakes of an early snow 

 upon the dead leaves of an autumnal forest in the north. After the 

 flowers fall, the naked branches of the inflorescence are themselves 



