THE "WILD WHEAT OF PALESTINE 301 



therefore regard our cultivated wheats as sexually degen- 

 erate. Since the wild wheat of Palestine has cross-fer- 

 tilized flowers, there seems good reason for supposing that 

 in our cultivated wheats self-pollination came to replace 

 cross-pollination under conditions of domestication. 



An attempt will now be made to summarize some of the 

 chief observations which have been made upon the open- 

 ing of the flowers and mode of pollination of our common 

 wheats. 



The results of careful observation by botanists and 

 cerealists upon the pollination of cultivated wheats seem 

 to show: (1) that in cooler northern regions, such as 

 northern Europe, the northern part of the United States, 

 and Canada, self-pollination is the rule but that cross- 

 pollination may and does take place occasionally, (2) that 

 in warmer regions cross-pollination is more frequent, and 

 (3) that in hot dry localities, such as the canal colonies 

 of the Punjab where the crop can only be grown by means 

 of irrigation, cross-pollination is quite common.^* 



Delphino observed that at flowering time the glumes 

 diverge rapidly and suddenly. At the same time, the an- 

 thers project laterally, open, and empty about one-third 

 of their pollen on the stigmas of the same flower, while 

 the rest of the pollen is scattered in the air. This happens 

 in about one minute and, after a quarter of an hour, the 

 glumes close again. Delphino made experiments which 

 prove that automatic self-pollination results in the setting 

 of good fruits.^" 



Delphino and Kornicke found that a single wheat flower 



18 A. Howard, Gabrielle L. C. Howard, and Rahman Abdur, The 

 Economic Significance of Natural Cross-fertilization in India, Me- 

 moirs of the Department of Agriculture in India, botanical series. 

 Vol. Ill, October, 1906. 



20 Vide P. Knuth, Handbook of Flower Pollination, translated by 

 J. R. A. Davis, Oxford, Vol. Ill, 1909, p. 529. 



