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 Avere sometimes regarded as being yellow 
or brown. The kernel color was used by Koernicke and Werner 
