350 



Bulletin 313 



Fig. 89. — Variation in apex of head 



be due to disease or to accidental injury, is apparently a heritable 



character. 



Many other differences of characters would doubtless be found in parts 



of the head, such as narrow 

 and broad glumes, but they 

 would probably be of no value 

 economically other than for 

 the differentiation of varieties. 

 Indeed, the head characters as 

 a whole are apparently of 

 little importance from the 

 breeding standpoint, other 

 than as distinguishing 

 varieties or races. The main 

 factor of interest is found in 

 the relation of the size of 

 head to seed production. A 

 large head is necessary if large 



seed production is desired, and a mediimi-sized head if medium seed 



production is desired. The relation of the amount of seed produced to the 



relative yield of hay, the relative yield of nutrients, and the relative yield of 



digestible nutrients per acre, must be determined before a definite policy 



can be formulated with reference to the size of head that the best type 



of timothy should have. No data on this subject are yet available, so 



far as the writer is informed. 



In general, the writer has 



assumed that in a hay and 



forage crop of this nature it is 



desirable to have the nutrients 



largely distributed in the 



stems and leaves, rather than 



concentrated in the seeds. If 



the nutrients are confined 



largely to the seeds and these 



ripen, considerable numbers 



of them may pass through 



the animal undigested and 



thus be lost. Should we favor 



the concentration of the 



nutrients in the seed by selecting types giving large yields of seed, we 



should probably lessen thereby the relative amount of nutrients in the 



stems and leaves. This problem must be thoroughly investigated chemi- 



Fig. 90. — Variation in base of head 



