26 BULLETIN 1074, U. S. DEPARTMENT OF AGRICULTURE. 
Grantham (98) showed that tillering is a varietal characteristic to a 
limited extent. He also showed that — 
Since the number of tillers a wheat plant produces is dependent upon so 
many environmental conditions a number of observations must be made in 
order to establish in which degree this tendency is exhibited. For this reason 
it is difficult to classify varieties closely as to their tillering habit. 
The degree of tillering, therefore, is of little value for classification 
purposes and is not used in the descriptions. A few varieties, such 
as Turkey, usually have a large number of culms per plant, while 
durum varieties have comparatively few. 
HEIGHT OF THE PLANT. 
The height of the plant also is often an important economic factor 
in wheat production, because it may determine the method or ease of 
harvesting. Height is measured from the surface of the ground to 
the tip of the spike, not including the awns of awned varieties. In 
regard to height, all varieties of wheat have been placed in the three 
classes — short, midtall, and tall. These are characters of minor 
value for classification and are used only for separating or dis- 
tinguishing otherwise closely related varieties. The principles gov- 
erning the grouping of varieties as early, midseason, and late apply 
here also. As an example, under California conditions wheats from 
12 to 36 inches in height would be classed as short; wheats from 24 
to 48 inches in height would be called midtall, and wheats from 36 
to 60 inches high would be considered tall. In most other sections of 
the country these differences would not be as great. In order to use 
the height of the plant as a character, the height of certain varieties 
must be determined and used for comparison. 
STEM CHARACTERS. 
There are three characters in the stem of wheat varieties which 
are useful in classification, namely, height, color, and strength. 
Height already has been considered as a plant character. 
COLOR OF THE STEM. 
All varieties of wheat are here classified as having white or purple 
stems. The colors of the stem and the variations that exist are shown 
in Plate III, Figure 1, a and h. These characters are of minor im- 
portance in classification; for in many localities and in some seasons 
the purple color common to a large number of wheat varieties does 
not become apparent. This often is the case under conditions of ex- 
treme drought and also under conditions of excessive moisture. Un- 
der favorable conditions, however, this stem color is very apparent 
during a week or 10 days in the ripening period. When apparent, the 
color differences are very useful in distinguishing varieties. The 
