UNITED STATES DEPARTMENT OF AGRICULTURE 



) BULLETIN No. 971 d^^ 



S>J^'<f^U 



Contribution from the Burean of Plant Industry 

 WM. A. TAYLOR, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



December 3. 1921 



INHERITANCE OF RAMOSE INFLORESCENCE IN 



MAIZE. 



By J. H. Kempton, Assistant in Crop Acclimatization. 



CONTENTS. 



Page. 



The ramose ear variation in maize_- 1 



Description of the parents 3 



First generation 4 



Second generation 5 



Correlation of the ear characters of 



the second generation 7 



Page. 



Third generation 8 



Fourth, generation 9 



Discussion 13 



Conclusions 18 



Literature cited 20 



THE RAMOSE EAR VARIATION IN MAIZE. 



From the standpoint of the origin of the ear of maize, perhaps the 

 most instructive variation is the ramose type of inflorescence discov- 

 ered by Gernert (4)^ in a strain of Learning Yellow Dent. In this 

 variation the simple pistillate inflorescence is replaced by a com- 

 pound structure which resembles somewhat the staminate inflores- 

 cence. Practically all the grain is borne on branches, the central 

 axis bearing seeds at the extreme apex only. (PI. I ; see also PL X.) 

 The larger surface on which seeds may be borne increases the po- 

 tential production, although the actual yield of grain is much less 

 than on normal plants of the parental variety. A single ramose ear 

 has been found to produce 4,700 pistils (PI. II), while the production 

 of one-quarter of that number would be unusual on an ear of the 

 parental Leaming variety. The failure to produce grain in quan- 

 tity commensurate with the number of pistils seems to be due, at 

 least in part, to the mechanical difficulty of exserting such a large 

 number of pistils through the ends of the husks, although there 

 doubtless are other restricting factors. 



» Serial numbers in parentheses refer to " Literature cited " at the end of this bulletin. 

 51551° — Bull. 971—1921 1 



