Transpiration as a Factor in Crop Production. 169 
Fig. 22. — The product from four plants of milo, four plants of Hogue's Yellow 
Dent corn, and four plants of Black Amber sorghum. Grown in potometers. 
1914. 
of drouth in a relatively dormant state and resume growth when 
moisture comes, whereas corn does not so fully possess this 
quality. 
WEEDS. 
The common wild sunflower (Helianthus annuus) was com- 
pared with Hogue's Yellow Dent corn, which is a standard 
variety. The results may be summarized as follows: 
Hogue's Yellow Dent corn 
Wild sunflower 
Dry 
matter 
Water 
require- 
ment 
Total 
water used 
per plant 
Grams 
558 
863 
Grams 
272 
588 
Kilograyyis 
151.7 
507.0 
The sunflowers used more than three times as much water 
per plant as the corn, while the water used per unit dry matter 
was slightly more than double that of the corn. It is not unusual 
