38 BULLETIN 1074, U. S. DEPARTMENT OF AGRICULTURE. 



scribed have beaks longer than 3 mm. Variations in beak lengths 

 are shown in Figure 9. 



AWN CHARACTERS. 



Certain characters of the awn are distinct. Some of these are of 

 some importance in classification, while others are not. The diver- 

 gence of the awn from the vertical is one of the latter. The awns 

 of some varieties are all nearly vertical or appressed, while others 

 are spreading. These characters are affected by drought or other 

 abnormal conditions and usually are not sufficiently constant for 

 classification purposes. The awns of some varieties sometimes are 

 deciduous, dropping off at maturity. This occurs so rarely, however, 

 that it is of little or no use in classification. 



The color and length of the awns, however, are factors of some 

 importance in this classification. 



COLOR OF THE AWN. 



In the key to the varieties of durum wheat the awn color is used 

 as the fourth major character. This method was followed by Koer- 

 nicke and Werner. For the other species and subspecies the awn 

 color is used only as a minor character. All awns are described as 

 white or black. The awn colors and variations in color are shown 

 in Plate III, Figure 1, c, d, e, and /. The white class may include 

 yellowish shades, and the black class may include shades of brown 

 and blue. Few varieties of common wheat have really black awns. 



LENGTH OF THE AWN. 



The length of the awn in awned varieties or of the apical awns of 

 varieties described as awnless is of slight value in classification. No 

 attempt has been made in these studies to separate the varieties into 

 classes with respect to awn length. In all descriptions, however, the 

 average extreme lengths are recorded in centimeters. 



KERNEL CHARACTERS. 



The kernel color, length, and texture are the most constant of all 

 the kernel characters. These are used as major distinctions. The 

 shape of the kernel is considered only of minor importance, as are 

 certain differences of the germ, crease, cheeks, and brush. 



COLOR OF THE KERNELS. 



Kernel colors were early recognized as important characters in 

 separating varieties. Most varieties were observed to have either 

 white or red kernels, but were sometimes regarded as being yellow 

 or brown. The kernel color was used by Koernicke and Werner 



