April 1, 1920 



A Teosinte-Maize Hybrid 



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In normal maize the number of rows of alicoles is always half the num- 

 ber of rows of grains. In the hybrid plants, however, 4-rowed spikes 

 may consist of either two rows of alicoles, each with 

 two seeds, or four rows of alicoles, each with a single 

 seed. Plants exhibiting the range of variation with 

 respect to the pistillate inflorescence are shown in Plates 

 2 to 5. 



As a basis of comparing the pistillate inflorescences 

 of the hybrid plants, the best-developed spike on the 

 third branch from the top of the plant was chosen and 

 the number and nature of the alicoles were recorded. To 

 eliminate as far as possible differences associated with 

 the size of the spike, the number of alicoles of the 

 classes single male, double male, single female, double 

 female, and mixed (one male and one female) was ex- 

 pressed as a percentage of the total number of alicoles 

 in the spike. 



DOUBLE MALE ALICOLES 



Neither maize nor teosinte normally produces male 

 spikelets in the pistillate inflorescences. In the Fj hybrids, however, out 

 of 123 plants in which the nature of the pistillate inflorescences was 

 determined, 18 had some alicoles with two staminate 

 spikelets, in 2 plants the number being as high as 50 per 

 cent (fig. 16), 



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Fig. 16. — Double male 

 alicoles: frequency 

 distribution of plants 

 in Fa Class value, 

 10 percent. 



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MIXED ALICOLES 



Mixed alicoles are not a character of either maize or 

 teosinte. There were, however, 13 Fg hybrid plants with 

 mixed alicoles, the highest percentage being 40 (fig. 17). 



SINGLE FEMALE ALICOLES 



Single female alicoles are a universal character of 

 teosinte, while in maize no variety is known in which 

 the seeds are not paired. Single female alicoles may 

 occur in rare instances on a part of an ear of maize where 

 the number of rows is reduced toward the tip. 



In the F2 hybrid plants, although there was practi- 

 cally a continuous series from o to 100 per cent, there 



Fig. 17. — Mixed ali- 

 coles: frequency 

 distribution of 



piantsinFs. Class wcrc distiuct indications of a tendency to segregate into 

 value. 10 percent, ^j^^ ^^^ parental forms, there being two modes, one at o, 

 the other at 100 (fig. 18). The numbers at these two modes were 34 

 and 12, indicating that the maize character is dominant. 



