50 



of the vegetation of the Wicklow Mountains on the Southeast 

 coast of Ireland, and of peat bogs from the vicinity of Dublin. 

 After considerable discussion the meeting adjourned at 9:40 

 P.M. D. Elizabeth Marcy 



Recording Secretary 



Meeting of December 15, 1937 



President Barnhart called the meeting to order at 3:40 p.m. 

 at the New York Botanical Garden. Seventeen persons were 

 present. The minutes of the November 17th and December 7th 

 meetings were read and approved. 



The recording secretary reported the deaths of Miss Sara F. 

 Passmore on September 19, 1937, and of Dr. J. J. Taubenhaus 

 on December 13, 1937. 



For the scientific part of the program, Dr. B. O. Dodge of 

 the New York Botanical Garden reported on several diseases 

 of Opuntia and showed interesting photographs and paintings 

 of the diseased plants. The fungus which caused one of these 

 diseases he found hard to classify, although an Ascomycete 

 and probably one of the Perisporiales. 



Prof. E. B. Matzke of Columbia University was the speaker 

 of the afternoon. He discussed "Infloresence patterns and the 

 effect of soil fertility on sexual expression in Begonia semper- 

 florens.'' He stated that the factorial interpretation frequently 

 adequately explained sex differences in the lower plants, but 

 that in the higher plants environment had been found to play 

 a large part in sex determination. In the angiosperms a plant is 

 never absolutely staminate or absolutely pistillate. It has been 

 observed that it is possible to reverse the sex of plants, in some 

 cases a plant producing staminate flowers being induced to 

 produce pistillate ones by more heavy feeding. 



In Prof. Matzke's study of Begonia semperflorens he ob- 

 served that the flowers which opened first in an infloresence 

 were staminate, those opening later, pistillate. The ratio of 

 staminate to pistillate flowers in any one infloresence varied, 

 but any two plants which had the same ratio also had branching 

 patterns which were either alike or the mirror image of one 

 another. He also observed that there was a greater proportion 

 of staminate flowers when the plants were grown under unfavor- 

 able conditions. 



