DISTINCTIONS IN CULTIVATED BARLEYS. 



11 



Table I. — Influence of geographical location on the length of the culm in 13 

 • representative selections of barley grown at four widely separated points, the 

 selections being arranged in the order of their height at each point.- 



St. Paul, Minn. 



Williston, N. Dak. 



Moccasin, Mont. 



Chico, Cal. 



Hordeum vulgare 



Servian 





S. P. I. No. 20375. 





Hordeum vulgare 







Hordeum vulgare 



Smyrna 









Servian. 





Oderbrucker 











S. P. I. No. 20375 



Kitzing, 6-rowed 











S. P.I. No. 20375 



Surprise 







Kitzing, 6-rowed 



S. P. I. No. 20375 





Kitzing, 6-rowed. 





Smyrna 





Kitzing, 2-rowed. 

 Surprise. 

 Hordeum vulgare. 







Kitzing, 2-rowed 



Princess 





Kitzing, 2-rowed 





The great variation evidenced by these few selections is sufficient 

 to show that the length of culm can not be of much taxonomic A^alue. 

 There are varieties which are persistently below average height, and 

 others that are as persistently above, but beyond that it is difficult to 

 make an unqualified statement. Locally, this measurement is of 

 more significance and can often be used to advantage in the study of 

 nursery selections. The differences it reveals are important in 

 breeding, no matter to what cause they may be due. 



DIAMETER OF THE CULMS. 



Measurements have not been found very useful in revealing small 

 differences in the diameter of the culm. The experimental error is 

 large, owing to the fact that the diameter varies on the same plant 

 with the culm selected, on the same culm with the internode chosen, 

 and on the same internode with the distance from the node. A part 

 of this variation was avoided by measuring the greatest diameter of 

 the first elongated internode, but even then the results were unsatis- 

 factory. There are varietal differences, but they must be great 

 enough to be seen optically before the error of measurement is re- 

 duced to the point where it becomes negligible. As a group, the 

 nutans has smaller culms than the Manchuria, but among the Man- 

 churia strains there is little difference. Only once in these investi- 

 gations has this character been used to isolate a type. This type has 

 proved to be stable, and perhaps the effort of measuring hundreds of 

 selections is rewarded by the one strain obtained, as it is very prom- 

 ising. 



THICKNESS OF CULM WALLS. 



A large number of determinations were made of the thickness of 

 the walls of the culm, with even less satisfaction than in those of the 

 diameter. Measurements finer than one-tenth of a millimeter are 

 impracticable, owing to the variation within the plant and culm. 

 This does not give range enough to disperse the varieties. For in- 



