36 BULLETIN 878, U. S. DEPARTMENT OF AGRICULTURE. 
years has averaged 4.6 days later. The average difference in time of 
maturity between Preston and Marquis during 50 station years is only 
0.8 day, showing the Preston variety to be less than one day later 
than Marquis. All varieties of durum wheat grown are later than 
Marquis, except the Algeria, which has been grown only at Highmore, 
S. Dak. Most varieties of durum wheat mature in about the same 
average period of two to four days later than Marquis under the same 
conditions. 
HEIGHT OF PLANT. 
The height of the wheat plant is of economic importance because it 
determines the methods or ease of harvesting. The height of differ- 
ent varieties of wheat, as measured from the surface of the ground to 
the tip of the spike, has varied greatly in these experiments. The 
average height of Marquis wheat during 57 station years in this semi- 
arid section is 29.4 inches, but its stature has varied from 17 to 48 
inches. The height of Marquis wheat at Dickinson, N. Dak., was 
43 inches in 1915 but only 18 inches in 1919. The height of the wheat 
plant is determined by the amount of elongation of the internodes of 
the culm and is influenced by numerous soil and climatic factors. In 
the northern half of the Great Plains the height is affected chiefly by 
the climate, including the amount of soil moisture, which is the result 
of the annual precipitation. The height of the wheat plant is in- 
creased by high soil fertility, abundant moisture, humid atmosphere, 
moderately cool temperature, and other factors which favor vegeta- 
tive growth at the time of heading. In general, early varieties are 
shorter than late varieties. Late varieties, which are normally quite 
tall, are sometimes shorter than short early varieties in seasons having 
drought or hot winds at heading time. When the drought, tempera- 
tures, or hot winds are extreme, the heads of wheat may not be 
entirely exserted from the sheath. 
The height of plant of 38 varieties of spring wheat grown at one or 
more of 1 1 stations in the northern half of the Great Plains area dur- 
ing three or more station years from 1913 to 1919 is shown in Table 
XVI. 
The Marquis variety is shorter than most of the common wheats and 
than all but one variety of durum wheat. The Galgalos and Huron 
varieties are both taller than the Marquis under favorable conditions, 
but they are easily affected by dry soil and atmosphere, so that their 
height is less than Marquis in many dry seasons. During 18 station 
years the Huron had an average height of 0.8 inch less than Marquis, 
while during 20 station years the Galgalos had an average height of 
2.0 inches less than Marquis. During 44 station years Power Fife has 
averaged 0.1 inch shorter than Marquis. At Williston, N. Dak., 
however, where climatic conditions are favorable for Power Fife, it is 
from 2 to 4 inches taller than Marquis. In that district and a few 
