350 TEXTBOOK OF BOTANY 



fruits. What can one do that will result in the initiation of flowers in 

 such plants? It has been known for a long time that if a branch of one 

 of these trees is girdled (ringed), it will bear flowers and fruits sooner 

 than other branches on the tree. If the trunk of the tree is girdled, numer- 

 ous branches on the tree will bear flowers and fruits sooner. If one wishes 

 to avoid killing the tree in this way, the girdle should be very narrow, 

 about one-eighth of an inch. It should be so protected that no parasites 

 can enter the wound and that complete healing by the growth of a new 

 cambium over the wound can occur within a few months. Merelv cut- 

 ting through the bark by drawing a knife blade around the trunk of the 

 tree may be as effective in initiating flowers as making a wider girdle. 

 How may one explain the initiation of flowers that results from girdling? 



REFERENCES 



Berth wick, H. A., and M. W. Parker. Initiation of flowers in soybean. Bot. 



Gaz. 100:374-387. 1938. Ibid. 651-689. 1939. 

 Garner, W. W. Recent work on photoperiodism. Bot. Rev. 3:259-275. 1937. 

 Gourley, J. H., and F. S. Hewlett. Ringing applied te the commercial orchard. 



Ohio Agr. Exp. Sta. Bull. 410. 1927. 

 Hamner, K. C, and James Benner. Initiation of flowers in cocklebur. Bot. 



Gaz. 100:388-431. 1938. 

 Loehwing, W. F. Initiation of flowers in soybean. Proc. Soc. Exp. Biol, and 



Med. 37:631-634. 1938. 

 Thompson, H. C. Temperature in relation to vegetative and reproductive 



development in plants. Proc. Amer. Soc. Hort. Sci. 37:672-679. 1939. 

 Numerous other publications are cited in the above publications. 



