RAMOSE INFLORESCENCE IN MAIZE. 3 



cences, and is readily classified qualitatively, while the component 

 parts are numerous and subject to definite quantitative study. 



DESCRIPTION OF THE PARENTS. 



In the selection of a variety to cross with Ramosa, fortunately 

 one was found which, in tassel dimensions, varies from the normal 

 almost as much as the Ramosa, but in the opposite direction. The 

 staminate inflorescence of this variety is of the familiar form, but 

 it is extreme in having relatively few branches and a central spike 

 which in some cases is half a meter in length (PL III). The pistil- 

 late inflorescence is normal, consisting of a single spike with 12 to 

 16 rows of seeds. This variety was collected by Dr. Pahner at 

 Chihuahua, Mexico, and its native name Gordo has been retained. 



Three crosses were made between the two types, Ramosa plants 

 being used as female parents. These hybrids were designated 

 Mhl57, Mhl58, and Mhl59. A few first-generation plants were 

 grown and self-pollinated, furnishing seed for the second genera- 

 tion. First-generation plants were grown again in larger numbers 

 when the second-generation progenies were planted. 



Fourteen characters were recorded for the second generation. 

 These characters fall into two groups, those relating to the terminal 

 staminate inflorescence and those relating to the pistillate inflor- 

 escence. 



TASSEL GROUP. 



Type of tassel : The tassels were classified into ramose or normal from their 

 general appearance. 



Length of the branching space : The length of the rachis in centimeters from 

 the lowest tassel branch to the uppermost. 



Length of the central spike : The length in centimeters of the single spike 

 from the uppermost tassel branch to the tip of the spike. The combination of 

 this measurement with that of the branching space gives the total length of 

 the tassel. 



Length of the uppermost tassel branch : The length in centimeters of the 

 uppermost branch of the tassel. In ramose inflorescences it often is difficult to 

 determine where the branches end and the pediceled spikelets begin. 



Length of the lowest tassel branch : The length in centimeters of the lowest 

 primary branch of the tassel. 



Total number of branches : This measurement includes all primary and 

 secondary branches as well as branches of a higher order. 



Central spike index : The length of the central spike as a percentage of the 

 total tassel length. 



EAR GROUP. 



Type of ear : Classified into ramose and normal from general appearance. 



Number of branches : The number of branches on the ear. In typical ramose 

 ears it is difficult to determine the total number of branches, since those at the 

 apex are much subject to environmental influence. It has been the practice to 

 record any ear with more than 50 branches as ramose. 



