CLASSIFICATION OF AMERICAN WHEAT VARIETIES. 



37 



small, and general observation is the only basis for describing them. 

 Those that are wider than the average are called wide, and those that 

 are narrower are called narrow. 



SHAPE OF THE BEAK. 



The apex of the beak varies considerably in shape. It is described 

 as obtuse, acute, and acuminate. Obtuse beaks are blunt at the apex. 



Fig. 7. — Beak widths : a, Narrow ; 

 6, midwide ; o, wide. (Natural 

 size and enlarged 3 diameters.) 



Fig. 8. — Beak shapes: a, Obtuse; t, 

 acute ; cv, acuminate. (Natural size 

 and enlarged 3 diameters.) 



Acute beaks come to a point at the apex. Acuminate beaks are nar- 

 rowly and very sharply pointed. All awned spikes have acuminate 

 beaks. These shapes are shown in Figure 8. 



LENGTH OF THE BEAK. 



Beak lengths are quite variable, especially in the awned varieties, 

 and are considerably influenced by environment. In general, condi- 

 tions which increase or decrease the 

 length of the beak affect nearly all 

 varieties to a similar degree. In the 

 awnless wheats the differences in 

 length are not great, but in many va- 

 rieties they are quite distinct. The 

 length of the beak is measured from 

 the shoulder of the glume upward. 

 On most awned wheats the length 

 increases from the base of the spike 

 to its apex. The range of differ- 

 ence varies greatly with the variety. 

 For this reason no definite measurements are used in describing the 

 lengths, but instead the average maximum and minimum lengths are 

 recorded in millimeters. None of the awnless varieties here de- 



FlG. 



9. — Beak lengths, showing seven 

 variations. (Natural size.) 



