158 



:\IEMOIRS OF THE XEW YORK BOTANICAL GARDEN 



lowing forenoon (in B varieties) and the second opening of the 

 sets following may be correspondingly delayed. On days when 

 this occurs there be a very general and complete reversal 

 in the daily alternation normal to the varieties (see record for 

 May 17 in chart 8). Flowers in the first period of opening may 

 be held in this condition for some time, even continuing thus over 

 night from one day to another. 



Sets of flowers subjected to sudden lower temperatures while 

 in the interval exhibit irregular behavior in the second opening. 

 This may be delayed, prolonged, or even omitted. The various 

 flowers of a single set may behave quite differently. 



A decided change from a period of cold inclement weather, 

 during which there was much delay in the opening of sets of 

 flowers, to Avarmer weather favorable to normal flower-behavior 

 sometimes brings three different sets of flowers into opening 

 between sunrise and sunset (see record for May 19 in chart 8). 



In response to decided changes in temperature the blooming 

 of all varieties is thrown off-stride and marked irregularities ap- 

 pear in nearly every aspect of flower behavior. The records of 

 charts 6 and 7 (see explanation with charts) are fairly typical 

 of such behavior. 



Comparing the season of bloom of 1925 in Florida with that 

 of 1923 in California for the orchards in which the writer made 

 observations, it can be said that in California there were many 

 more days of irregular behavior. 



Varieties differ in the degree and the type of irregularity 

 which they exhibit. The observations botli in California and 

 Florida indicate that the varieties of the B class exhil)it the 

 greatest irregularity and off-stride behavior under unfavorable 

 weather conditions. Weather which merely delays the opening 

 of the two sets on varieties of the A group will often cause vari- 

 ous varieties of the B group to continue a set of firsts open over 

 night and into the next day, or to skip a set of firsts, or to have 

 them open for a period during the night. See especially the 

 records here given for March 4 and 5 in chjVbt 6. 



Frequently during irregular and off-stride blooming there is 

 an overlapping of different sets and fi.rst-period flowers may be 

 open at the time second-period flowers are shedding pollen. 



