22 



Journal of Agricultural Research 



Vol. XIX, No. I 



SO 



■20 



In normal maize there would be no secondary branches bearing stami- 

 nate spikelets. In Florida teosinte the number is usually 2 or 3. In the 

 F2 hybrid plants the mean number was 2. The range was from o to 8. 

 Nearly half the plants had no staminate secondaries and there is almost 

 no indication of a second mode (fig. 1 5) . 



Nearly all the significant correlations not readily assignable to 

 physiological relations are disherent. Thus height, total leaves, and 

 circumference index in the height group, secondary branches and 

 secondary index in the tassel group, branch silking first, and days to 

 pollen all show disherent correlations. Many of these are related, since 

 they would be similarly affected by changes in vigor, but it is difficult to 

 understand why increased vigor should result in a 

 smaller number of male secondaries; and the nega- 

 tive correlation with secondary index is difficult to 

 understand as other than genetic. 



The absence of correlation between male second- 

 aries and male branch index, which are placed in 

 the same group because both are measures of the 

 tendency to produce staminate spikelets, is in itself 

 an indication of disherence. 

 \/o 



CHARACTERS OF THE PISTILLATE INFLO- 

 RESCENCE 

 ALICOLE GROUP 



To discuss the characters of the pistillate inflo- 

 rescence of the hybrids between maize and teosinte, 

 a short preliminary description is necessary. 



In maize both staminate and pistillate spikelets 

 are borne in pairs. In the pistillate inflorescence 

 each pair of spikelets occupies a pit or alveolus 

 In the staminate inflorescences there is only a faint suggestion of an 

 alveolus. In teosinte the arrangement of the staminate spikelets 

 is like that in maize; but in the pistillate inflorescence the spikelets are 

 borne singly, each occupying a highly specialized alveolus. In hybrids 

 of maize and teosinte, all permutations of the above arrangements 

 occur, and to facilitate description the term alicole is used for the 

 spikelet or spikelets arising from a single alveolus or having a common 

 origin. Thus an alicole may consist of one or more staminate spikelets, 

 one or more pistillate spikelets, or both pistillate and staminate spikelets.^ 



J For a more complete discussion of tlie pistillate inflorescence of teosinte and maize hybrids see 

 Collins, G. N. structurs of thb maize ear as indicated in zsa-euchlaena hybrids. In Jour. 

 Agr. Research, v. 17, no. 3, p. 127-135, i fig., pi. 16-18. 1919. 



Fig. 15. — Male secondaries: 

 frequency distribution of 

 plants in F2. Clas s 

 value, one branch. 



