Water-Content of Plants 45 



mere presence of the numerous tough roots and crowns 

 are sufficient to leave the soil in bad physical condition. 

 This unfavorable condition restricts the absorption of 

 water by the soil during fall and winter, and discourages 

 the requisite preparation for the succeeding crop. Owing 

 to these facts, sorghum land commonly shows a defi- 

 ciency in moisture the following spring. 



The rooting habit of the sugar-beet, according to Ten 

 Eyck, indicates that it is a deep " feeder " at least during 

 the late stages of growth. The roots of potato seem to 

 occupy the soil as completely as any crop, and a consider- 

 able number penetrate to a depth of two or three feet; 

 yet many of the deep-rooted individuals possess a surpris- 

 ingly small number of feeding roots, at least on plants 

 examined in the autumn. 



Nobbe measured the root-system of a wheat plant about 

 one year old and found the aggregate length of the roots to 

 be 500-600 meters (545-655 yards), while that of a full- 

 grown pumpkin vine measured about 50 times as long, 

 or about 25 kilometers (15f miles). The rooting habits 

 of shade trees are particularly worthy of study, especially 

 in view of the difficulties experienced with trees in towns 

 and cities. 



From the studies in narrow boxes made by Rotmi- 

 strov it has been shown that a large number of farm 

 crops penetrate both loamy and sandy soils to a depth of 

 one meter or more. 



30. The production of root-hairs. - The roots and mi- 

 nute rootlets which in a complete root-system are read- 

 ily evident to the eye are, however, secondary with respect 

 to the relations existing between the plant and the soil 



