April I, 1920 



A Teosinte-Maize Hybrid 



17 



(fig. 7) is decidedly skew, more than half the plants having one, but there 

 is no indication of bimodality. 



In maize there is always an intravarietal correlation between nodes 

 above and total number of leaves and other characters that are expres- 

 sions of size. Since Tom Thumb maize is smaller and has a much smaller 

 number of leaves than teosinte, coherence with these size characters 

 would not be masked by physiological correlations. 



It is therefore interesting to note that the tassel characters, which in 

 pure strains of maize are positively correlated with nodes above, are here 

 negatively correlated, affording clear evidence of coherence. There are 

 also significant correlations in the direction of co- ^^ 



herence v/ith the male branch characters and node I 



silking first. There are no significant disherences. 



-5^ 



NODES ABOVE ON THIRD 



SO 



I 



< /o 



In all varieties of teosinte the number of nodes above 

 the uppermost secondary on the third branch is one, 

 as on the main culm. In maize the value will depend 

 on what is considered the homologue of the third 

 branch from the top in teosinte. Taken strictly, the 

 upper branch in maize is the ear, and the third branch 

 from the top, v/hen such exists, would be an earlike 

 branch that in some types vv^ould partake somewhat 

 of the nature of a sucker. If sufficiently suckerlike, the 

 number of nodes above the uppermost secondary of 

 such a branch would correspond to those of the main 

 stalk, that is, the range v/ould be from 3 to 8. If, how- 

 ever, the ear of maize be assumed to correspond to 

 some branch below the uppermost in teosinte, those 

 above the ear having been suppressed, the number of 

 nodes above the uppermost secondary would be much 

 greater, for in this case the branch would be an ear 

 and the secondary branches would be the secondary 

 ears which almost invariably are borne in the axil of 

 the lowest husk. In any case the number would be 

 larger in maize than in teosinte. 



This character was recorded for three of the F^ plants. In two of 

 these the number was i; in the other it was 2. The average number 

 in the Fj hybrid plants was i .78, with no indication of bimodality. The 

 distribution (fig. 8) is much less skew than for the nodes above on 

 the m^hi^cjim, the mode being at 2. In its correlations, this character is 

 similar to nodes above on the main stalk, 

 164175°— 20 2 



ffl 



Or/VOO£S 



Fig. 7. — Nodes above: 

 frequency distribu- 

 tion of plants in F2. 

 Class value, onenode. 



