April 1, 1920 



A Teosinte-Maize Hybrid 



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LENGTH OP PROPHYLLARY 



This character is closely associated with the number of spikes in the 

 prophyllary, and like that character it distinguishes sharply between the 

 parental varieties and species. 



The mean length of the prophyllary branch in 87 plants of Florida 

 teosinte was 10.8 cm. The mean length in the 

 F2 hybrid plants was 13.4 cm. There was some 

 evidence of two modes (fig. 24), one at o, the 

 other at 13. 



There are three significant coherent correla- 

 tions — namely, with male secondaries, nodes 

 silking index, and length of internode on third. 

 The correlation with position 

 of best spike is also signifi- 

 cant but disherent. 



Although prophyllary 

 spikes and length of pro- 

 phyllary have a positive cor- 

 relation of 0.59, the first is 

 negatively correlated with 

 position of best spike while the 

 correlation with the second is 

 negative. Thus, as the pro- 

 phyllary branch becomes 

 longer there are more spikes, 

 but they are smaller. 



mm 



NUMBER OF ROWS GROtJP 



ROWS IX CENTRAL SPIKE 



Fig. 34. — Length of prophyllary: 

 frequency distribution of plants 

 in F2. Class value, 4 cm. 





The number of rows of spikelets in the central spike 

 of the tassel is a close homologue of the number of rows 

 of seeds in the pistillate inflorescence. At first thought 

 ^ this might seem not to be the case in teosinte where 

 all the spikes of thestaminate inflorescence are 4-rowed 

 uarspikeT'frequen^ and thosc of the pistillate inflorescence are 2-rowed. 

 fn'^^F^" Qasf tlxS. '^^^^ apparent disagreement is occasioned by the sup- 

 one row. pression of one of each pair of spikelets in the pistillate 

 inflorescence, there being in each instance 2 rows of alicoles. 



In maize, so far as observ^ed, plants with 8-rowed ears always have 

 8-rowed central spikes. With the higher number of rows the arrangement 

 in the central spike becomes indistinct. 



