CLASSIFICATION OF AMERICAN WHEAT VARIETIES. ae 
The covering and coloring of the glumes are major characters of 
the second and third place, respectively. ‘The length and width of 
the glumes also are used, but are of only minor importance. 
COVERING OF THE GLUMES. 
Glumes of all varieties here discussed are described as glabrous or 
pubescent (Fig. 2). Host (779) placed the pubescent-glumed wheats 
in a separate species called Triticum villosum. Several later authors 
also considered pubescent wheats as different species. This character 
is used here, however, only as a major one in separating varieties, but 
is given the second place in the keys because 
of the definite and striking contrast between 
absence and presence. This action is in ac- 
cordance with the usage of Koernicke and 
Werner. 
Glumes described as glabrous are without 
any covering of hairs. Those described as 
pubescent are more or less covered with hairs 
of varying length. Pubescence usually is 
readily apparent. The degree of pubescence 
varies in the different varieties. On some the 
(ts Fie. 2—Glume covering: a, 
hairs are much longer andmorenumerousthan — glabrous; b, pubescent. 
on others. Glumes of some durum varieties (Natural size and en 
are partly glabrous and partly pubescent, but Oc ei mI sah 
are classed as pubescent. In such varieties the pubescence is most 
often found cn the edge of the glumes. 
COLOR OF THE GLUMES. 
Differences in glume color were early recognized. Lamarck (1/34) 
used these distinctions in classifying varieties. Glume color is here 
used as a major character and occupies third position in the key be- 
cause of the distinct differences which are readily apparent when 
the plants are mature. This is also in accordance with the usage of 
Koernicke and Werner (1/33). All glumes are classed as white, 
yellowish, brown, or black. These colors are shown in Plate III, 
Figure 2. 
Glumes classed as white may vary in color from a cream or pale- 
_ straw color to a dark yellow (PI. III, Fig. 2, a and 6). Practically 
{ no glumes are without color. Within the class, however, there are 
two rather distinct shades. Some taxonomists have classified them 
separately as white and yellowish. In the present bulletin, however, 
both shades are placed in the same class and described only by the 
one term “ white,” except in the case of the durums, which are classed 
separately as white and yellowish. In the descriptions the glumes 
of some varieties of common wheat are described as being yellowish 
95539°—22—Bull. 10743 
